Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0031417 NatC complex	IBA GO_REF:0000033	ACCEPT	Summary: NAA35 is a constitutive auxiliary subunit of the NatC complex; phylogenetic inference across MAK10 orthologs supports this membership, which is also directly demonstrated. Structural work (Grunwald 2020) shows NAA35 is the central scaffold that wraps around both NAA30 and NAA38 to hold the heterotrimer together. Reason: NatC complex membership is the defining cellular component of NAA35 and is well supported by phylogenetic and direct experimental evidence. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30. file:human/NAA35/NAA35-deep-research-falcon.md NAA35's primary role is to serve as the central assembly scaffold that organizes the NatC complex architecture and mediates its interaction with ribosomes, thereby enabling co-translational N-terminal acetylation of specific substrate proteins
GO:0043066 negative regulation of apoptotic process	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Knockdown of NatC subunits (including NAA35) induces p53-dependent apoptosis, implying that NatC activity normally suppresses apoptosis. This is a downstream biological-process consequence of NatC-mediated N-terminal acetylation, not a direct molecular activity of NAA35. Reason: Plausible process annotation derived from the apoptotic phenotype of NatC depletion; indirect and downstream of the complex's core acetyltransferase activity. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Involved in regulation of apoptosis and proliferation of smooth muscle cells
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: Electronic annotation of cytoplasmic localization, consistent with the experimentally documented cytoplasmic site of NatC. Reason: Cytoplasm is the principal, experimentally supported compartment of NatC. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0031417 NatC complex	IEA GO_REF:0000002	ACCEPT	Summary: InterPro-based electronic annotation of NatC complex membership, redundant with and consistent with stronger experimental evidence. Reason: Correct and well-corroborated NatC complex membership. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
GO:0005515 protein binding	IPI PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	KEEP AS NON CORE	Summary: IntAct interactions with NAA30 (Q147X3) and NAA38 (Q9BRA0), the other NatC subunits. The bare protein binding term is uninformative; the relevant interaction is NatC complex assembly. Reason: Records genuine intra-complex interactions but the uninformative GO:0005515 term is non-core; NatC complex membership captures the meaningful content. Supporting Evidence: file:human/NAA35/NAA35-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:19398576 UniProtKB:Q147X3
GO:0005515 protein binding	IPI PMID:32296183 A reference map of the human binary protein interactome.	KEEP AS NON CORE	Summary: Binary yeast two-hybrid interactome (HuRI) interaction with TRIM7 (Q9C029), an E3 ligase unrelated to NatC function. An isolated high-throughput interaction that does not inform NAA35's core role. Reason: Bare protein binding from a single high-throughput binary screen with a partner (TRIM7) outside the NatC complex; uninformative and not part of the core function. Supporting Evidence: file:human/NAA35/NAA35-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:32296183 UniProtKB:Q9C029
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	KEEP AS NON CORE	Summary: BioPlex interactome interactions with NAA30 (Q147X3) and NAA38 (Q9BRA0). Uninformative bare protein binding term reflecting NatC complex assembly. Reason: Real interactions with the other NatC subunits; non-core as a bare protein binding annotation, subsumed by the NatC complex term. Supporting Evidence: file:human/NAA35/NAA35-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:33961781 UniProtKB:Q147X3
GO:0005515 protein binding	IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func...	KEEP AS NON CORE	Summary: Multimodal cell-maps interactome interaction with NAA30 (Q147X3). Uninformative bare protein binding term reflecting NatC complex assembly. Reason: Real interaction with the NAA30 catalytic subunit; non-core as a bare protein binding annotation, subsumed by the NatC complex term. Supporting Evidence: file:human/NAA35/NAA35-goa.tsv GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:40205054 UniProtKB:Q147X3
GO:0048659 smooth muscle cell proliferation	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: Electronic annotation transferred from the mouse ortholog (EGAP), which was implicated in smooth-muscle-cell proliferation and embryonic vascular development. This is a peripheral, organism-specific developmental role. Reason: Transferred from mouse phenotype data; peripheral to NAA35's core NatC scaffold function and not a direct molecular activity. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Involved in regulation of apoptosis and proliferation of smooth muscle cells
GO:0005829 cytosol	IDA GO_REF:0000052	ACCEPT	Summary: Direct immunofluorescence (HPA) evidence for cytosolic localization, consistent with the cytoplasmic site of NatC. Reason: IDA-supported cytosolic localization matching the cytoplasmic ribosome-associated site of NatC. Supporting Evidence: file:human/NAA35/NAA35-goa.tsv GO:0005829 cytosol cellular_component ECO:0000314 IDA GO_REF:0000052
GO:0005737 cytoplasm	NAS PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	ACCEPT	Summary: Non-traceable author statement (ComplexPortal) of cytoplasmic localization, consistent with the documented cytoplasmic site of NatC. Reason: Consistent with the primary cytoplasmic localization of NatC. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0031417 NatC complex	IPI PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	ACCEPT	Summary: ComplexPortal/IPI evidence that NAA35 is part of the NatC complex, from the study that identified the human NatC complex. Reason: Direct experimental support for NatC complex membership. Supporting Evidence: PMID:19398576 the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
GO:0031417 NatC complex	IDA PMID:37891180 N-terminal acetylation shields proteins from degradation and...	ACCEPT	Summary: Direct experimental confirmation of NatC complex membership in the protein-shielding/longevity study. Reason: Well-supported NatC complex membership. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
GO:0005737 cytoplasm	IDA PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	ACCEPT	Summary: Direct experimental cytoplasmic localization of NAA35, consistent with ribosome-associated NatC activity. NAA35 in particular carries the principal ribosome-binding surface of NatC (an electropositive C-terminal tip region), so its cytoplasmic localization reflects co-translational action at the ribosome. Reason: Cytoplasm is the principal experimentally supported compartment of NatC. Supporting Evidence: PMID:19398576 This complex associates with ribosomes file:human/NAA35/NAA35-deep-research-falcon.md NAA35, as part of the NatC complex, localizes to ribosomes where it functions co-translationally
GO:0031417 NatC complex	IDA PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	ACCEPT	Summary: Direct experimental identification of NAA35 (hMak10) as an auxiliary subunit of the human NatC complex. Reason: Defining cellular component, directly demonstrated. Supporting Evidence: PMID:19398576 the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
GO:0043066 negative regulation of apoptotic process	IMP PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	KEEP AS NON CORE	Summary: Mutant-phenotype evidence that NAA35 (hMak10) knockdown induces p53-dependent apoptosis, indicating NatC normally suppresses apoptosis. Downstream consequence of complex function. Reason: Real phenotype-based process annotation, but indirect and downstream of NatC's core acetyltransferase activity. Supporting Evidence: PMID:19398576 results in p53-dependent cell death
GO:0005737 cytoplasm	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity-based annotation of cytoplasmic localization (from mouse ortholog), consistent with the documented cytoplasmic site of NatC. Reason: Consistent with the primary cytoplasmic localization of NatC; corroborated by IDA evidence. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm
GO:0048659 smooth muscle cell proliferation	ISS GO_REF:0000024	KEEP AS NON CORE	Summary: Sequence-similarity-based annotation transferred from the mouse ortholog (EGAP) linked to smooth-muscle-cell proliferation and embryonic vascular development; a peripheral developmental role. Reason: Transferred from mouse phenotype data; peripheral to NAA35's core NatC scaffold function. Supporting Evidence: file:human/NAA35/NAA35-uniprot.txt Involved in regulation of apoptosis and proliferation of smooth muscle cells
GO:0006474 N-terminal protein amino acid acetylation	IC PMID:19398576 Knockdown of human N alpha-terminal acetyltransferase comple...	NEW	Summary: NAA35/hMak10 is a non-catalytic auxiliary/scaffold subunit of human NatC, the complex responsible for cotranslational N-terminal acetylation. The acetyltransferase activity resides exclusively in the catalytic NAA30 subunit (GNAT fold); NAA35 contributes the scaffold and part of the NAA30-NAA35 substrate-binding interface but does not itself transfer the acetyl group. The involved_in (process) annotation is therefore appropriate, whereas a catalytic molecular-function term for NAA35 would not be. Reason: The review captures NatC complex membership but not the BP carried out by that complex. This recommends process involvement for the auxiliary subunit while explicitly not assigning catalytic acetyltransferase MF to NAA35. Supporting Evidence: PMID:19398576 the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31 PMID:19398576 the human NatC complex functions in cotranslational N-terminal acetylation file:human/NAA35/NAA35-deep-research-falcon.md It is crucial to emphasize that NAA35 itself does not possess catalytic acetyltransferase activity. The catalytic function resides exclusively in the NAA30 subunit, which contains the conserved GNAT (GCN5-related N-acetyltransferase) fold

Core Functions

Non-catalytic auxiliary/scaffold subunit of the NatC N-terminal acetyltransferase complex, required for assembly and function of NatC, which co-translationally acetylates N-terminal methionine residues of substrates with bulky/hydrophobic second residues.

Directly Involved In:

N-terminal protein amino acid acetylation

Cellular Locations:

cytoplasm

In Complex:

NatC complex

Supporting Evidence:

file:human/NAA35/NAA35-uniprot.txt
Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
PMID:19398576
the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
file:human/NAA35/NAA35-deep-research-falcon.md
NAA35's primary role is to serve as the central assembly scaffold that organizes the NatC complex architecture and mediates its interaction with ribosomes, thereby enabling co-translational N-terminal acetylation of specific substrate proteins

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000024

Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:19398576

Knockdown of human N alpha-terminal acetyltransferase complex C leads to p53-dependent apoptosis and aberrant human Arl8b localization.

NatC contains the catalytic subunit hMak3 (NAA30) and auxiliary subunits hMak10 (NAA35) and hMak31 (NAA38); the complex associates with ribosomes.
Knockdown of NatC subunits results in p53-dependent cell death, indicating NatC normally suppresses apoptosis.

PMID:32296183

A reference map of the human binary protein interactome.

PMID:33961781

Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.

PMID:37891180

N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity.

NatC-mediated N-terminal acetylation shields substrate proteins from degradation, promoting protein stabilization, motility and longevity.

PMID:40205054

Multimodal cell maps as a foundation for structural and functional genomics.

file:human/NAA35/NAA35-deep-research-falcon.md

Falcon deep research report for NAA35

NAA35 is the large non-catalytic auxiliary/scaffold subunit of the heterotrimeric NatC complex (with catalytic NAA30 and small auxiliary NAA38); it organizes the complex architecture, contributes to the NAA30-NAA35 substrate-binding interface that determines Met-hydrophobic specificity, and mediates ribosome association via an electropositive C-terminal tip region.

Suggested Experiments

Experiment: Reconstitute NatC in vitro with and without NAA35 to test whether the auxiliary subunit is required for catalytic activity and substrate selectivity of NAA30.

Experiment: Cryo-EM of the NatC-ribosome complex to map the NAA35 scaffold contacts with the ribosome and the catalytic subunit.

Experiment: N-terminomics of NAA35-depleted human cells to define the NatC-dependent N-terminal acetylome and test whether loss of the auxiliary subunit phenocopies loss of the catalytic subunit.

Deep Research

Falcon

(NAA35-deep-research-falcon.md)

Comprehensive Research Report: NAA35 (N-alpha-acetyltransferase 35, NatC Auxiliary Subunit) Falcon Edison Scientific Literature 24 citations 1 artifacts 2026-06-20T06:33:25.450055

Edison artifact artifact-00 (text/markdown)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Comprehensive Research Report: NAA35 (N-alpha-acetyltransferase 35, NatC Auxiliary Subunit)

Overview

NAA35 (UniProt Q5VZE5) encodes the large auxiliary subunit of the heterotrimeric NatC N-terminal acetyltransferase complex in humans (aksnes2023natsata pages 1-2). This protein, also known as MAK10 homolog or EGAP, belongs to the evolutionarily conserved MAK10 family and functions as an essential structural component of the NatC complex alongside the catalytic subunit NAA30 and the small auxiliary subunit NAA38 (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2). NAA35's primary role is to serve as the central assembly scaffold that organizes the NatC complex architecture and mediates its interaction with ribosomes, thereby enabling co-translational N-terminal acetylation of specific substrate proteins (grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 9-10).

Category	NAA35 / NatC summary	Key details specific to NAA35	Evidence
Gene/protein identity	Human NAA35 (UniProt Q5VZE5; MAK10 family) encodes N-alpha-acetyltransferase 35, NatC auxiliary subunit, a core component of the heterotrimeric NatC N-terminal acetyltransferase complex.	NAA35 is the large auxiliary subunit of NatC; literature consistently pairs it with catalytic NAA30 and small auxiliary NAA38.	(grunwald2020divergentarchitectureof pages 1-2, aksnes2023natsata pages 1-2, varland2023nterminalacetylationshields pages 1-2)
Complex composition	NatC is a heterotrimer composed of NAA30 (catalytic GNAT-fold subunit), NAA35 (large auxiliary subunit), and NAA38 (small auxiliary subunit). All three are important for normal NatC activity.	NAA35 serves as the central assembly/scaffold subunit linking NAA30 and NAA38.	(grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2)
Primary biochemical function of the complex	NatC catalyzes co-translational N-terminal acetylation: transfer of an acetyl group from acetyl-CoA to the free α-amino group of nascent polypeptides.	NAA35 is not the catalytic acetyltransferase; instead, it supports catalysis by organizing the NatC architecture and helping form the peptide-binding environment with NAA30.	(grunwald2020divergentarchitectureof pages 1-2, aksnes2023natsata pages 1-2, chang2023impactofprotein pages 4-5, grunwald2020divergentarchitectureof pages 9-10)
Subunit roles	NAA30 performs catalysis; NAA38 supports full activity/stability; NAA35 organizes the quaternary structure and contributes to ribosome association and substrate recognition.	NAA35 wraps around much of NAA30 and around NAA38, creating a highly intertwined complex and contributing residues/structure to the NAA30–NAA35 substrate-binding interface.	(grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 4-5, grunwald2020divergentarchitectureof pages 9-10, grunwald2020divergentarchitectureof pages 8-9)
Substrate specificity of NatC	NatC preferentially acetylates initiator methionine-retaining N-termini where Met is followed by a hydrophobic or amphipathic residue. Canonical classes include ML, MF, MI, MW; expanded in vivo profiling also supports MY, MK, MM, MA, MV, MS in yeast, with some redundancy from other NATs for certain classes.	NAA35 helps create the deeper, more confined peptide-binding pocket with NAA30 that explains NatC specificity for Met-hydrophobic N-termini.	(grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 1-2, grunwald2020divergentarchitectureof pages 6-7, damme2023expandedinvivo pages 1-2, grunwald2020divergentarchitectureof pages 9-10, nashed2023functionalmappingof pages 1-3)
Sequence determinants beyond position 2	NatC mainly recognizes the first two residues, but positions 3 and 4 also contribute strongly to efficient binding/catalysis; structural and kinetic studies showed improved activity for peptides optimized at these positions.	The NAA30–NAA35 interface helps accommodate the first four residues of cognate substrates.	(grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 6-7, grunwald2020divergentarchitectureof pages 9-10)
Example substrates / substrate classes	Known or cited NatC-dependent targets include UBE2M/UBC12, UBE2F, ARFRP1 (Arl3 in yeast), ARL8B, viral Gag, and mitochondrial precursor proteins with NatC-compatible N-termini.	Through supporting NatC-mediated acetylation of these proteins, NAA35 indirectly affects their stability, targeting, and pathway function.	(varland2023nterminalacetylationshields pages 1-2, varland2023nterminalacetylationshields pages 3-4, grunwald2020divergentarchitectureof pages 9-10, nashed2023functionalmappingof pages 1-3, aksnes2019cotranslationalposttranslationaland pages 4-5)
Cellular localization	NatC is a ribosome-associated NAT that acts co-translationally at or near the ribosomal exit tunnel on nascent chains; major NATs including NatC are associated with mono- and polyribosomes.	NAA35 contains the principal ribosome-binding surface of NatC.	(varland2023nterminalacetylationshields pages 1-2, grunwald2020divergentarchitectureof pages 8-9, grunwald2020divergentarchitectureof pages 10-11, aksnes2019cotranslationalposttranslationaland pages 4-5)
NAA35 tip region	Structural work identified an elongated ~30 Å protruding “NAA35 tip” region formed mainly by helices near the C-terminus.	The tip region is electropositive and required for efficient ribosome association; alanine substitutions in this region reduced NatC co-sedimentation with ribosomes without major catalytic defects in vitro.	(grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 8-9, grunwald2020divergentarchitectureof pages 10-11)
Structural fold/features of NAA35	NAA35 is mostly α-helical with a unique fold lacking close structural homologs in the PDB; it also contains short β-strands in the N- and C-terminal regions.	Its uniqueness supports a specialized NatC-specific scaffolding role rather than a generic NAT auxiliary architecture.	(grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 9-10)
Assembly architecture	NAA35 forms the central assembly hub of NatC. It wraps around almost the entire circumference of NAA38 and around three quarters of NAA30, helping generate a central tunnel and peptide-binding groove.	NAA35 connects NAA38 to NAA30 and is essential for proper NatC integrity; the N-terminus of NAA35 is important for NAA38 interaction.	(grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 4-5, grunwald2020divergentarchitectureof pages 9-10)
Contribution to catalysis	The catalytic residues reside in NAA30, but NatC catalysis depends on proper subunit organization. Mutations in selected NAA35 residues had only modest direct kinetic effects, whereas loss of NAA38 reduced kcat strongly; overall, all three subunits are required for full in vivo function.	NAA35’s main mechanistic role is architectural and positional, enabling efficient catalysis rather than donating the catalytic residues itself.	(grunwald2020divergentarchitectureof pages 6-7, damme2023expandedinvivo pages 1-2, grunwald2020divergentarchitectureof pages 9-10)
Protein quality control pathway	A major recent function of NatC is to shield Met-hydrophobic N-termini from degradation. In human cells, NatC loss exposes proteins to recognition by the UBR4–KCMF1 arm of the Arg/N-degron pathway.	NAA35 knockout showed strong positive genetic interactions with UBR4, KCMF1, UBR2, UBE2A and other quality-control genes, supporting NAA35’s role in this pathway as part of NatC.	(varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2, varland2023nterminalacetylationshields pages 3-4)
Vesicle/Golgi trafficking pathway	NatC supports subcellular targeting of specific small GTPases and trafficking proteins, including Golgi and lysosomal targeting pathways. Loss of NatC perturbs Golgi vesicle transport and related trafficking modules.	NAA35 knockout screens were enriched for negative genetic interactions with genes involved in Golgi vesicle transport, endosomal transport, virion assembly, vesicle organization, and included ARL1, SYS1, RAB2A, ARFRP1.	(varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2, varland2023nterminalacetylationshields pages 3-4, aksnes2019cotranslationalposttranslationaland pages 4-5)
Neddylation pathway	NatC-mediated acetylation of UBE2M and UBE2F increases their affinity for cognate E3 ligases, promoting cullin neddylation.	NAA35 participates indirectly by enabling NatC to acetylate these NEDD8-conjugating enzymes.	(varland2023nterminalacetylationshields pages 1-2, aksnes2019cotranslationalposttranslationaland pages 4-5)
Mitochondrial biology	NatC deficiency has been linked to reduced expression of mitochondrial proteins, loss of membrane potential, and mitochondrial fragmentation in human cells; yeast and comparative analyses also support a role in mitochondrial precursor handling/import.	NAA35, via NatC, likely contributes to acetylation of mitochondrial precursor proteins with NatC-compatible N-termini and thereby to mitochondrial proteome integrity.	(grunwald2020divergentarchitectureof pages 2-3, nashed2023functionalmappingof pages 1-3)
Development, aging, and organismal phenotypes	NatC perturbation affects cell growth, apoptosis, development, motility, and longevity across systems. In flies, loss of NatC caused reduced longevity and age-dependent motility defects; in zebrafish, NAA30 or NAA35 loss impaired development.	NAA35 is therefore functionally important beyond biochemistry, even though its effects are mediated through the NatC complex.	(grunwald2020divergentarchitectureof pages 2-3, varland2023nterminalacetylationshields pages 1-2)
Human disease relevance	Reviews and primary studies connect NAT dysfunction broadly to human disease; NatC components have emerging disease links. A de novo NAA35 variant has been reported in a patient cohort with cerebral palsy, though causal certainty remains limited.	Direct disease evidence for NAA35 is still sparse compared with NAA30/NAA10/NAA15, so current interpretation is suggestive rather than definitive.	(grunwald2020divergentarchitectureof pages 1-2, aksnes2023natsata pages 1-2)

Table: This table summarizes the identity, composition, function, localization, substrate specificity, structural biology, and pathway roles of human NAA35 as the large auxiliary subunit of the NatC complex. It is useful for quickly distinguishing NAA35’s scaffolding and ribosome-binding roles from the catalytic activity carried out by NAA30.

Primary Function and Role in the NatC Complex

The NatC Complex and N-Terminal Acetylation

The NatC complex catalyzes N-terminal acetylation (Nt-acetylation), which is one of the most abundant protein modifications in eukaryotes, affecting approximately 80-90% of the human proteome (aksnes2023natsata pages 1-2, varland2023nterminalacetylationshields pages 1-2). This irreversible modification involves the transfer of an acetyl group from acetyl-coenzyme A to the free α-amino group at the N-terminus of nascent polypeptide chains (grunwald2020divergentarchitectureof pages 1-2, aksnes2023natsata pages 1-2). NatC is one of the three major ribosome-associated N-terminal acetyltransferases (along with NatA and NatB) that collectively ensure the majority of cellular proteins receive this modification (aksnes2023natsata pages 1-2).

NAA35 as a Structural Scaffold, Not a Catalytic Subunit

It is crucial to emphasize that NAA35 itself does not possess catalytic acetyltransferase activity. The catalytic function resides exclusively in the NAA30 subunit, which contains the conserved GNAT (GCN5-related N-acetyltransferase) fold (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, chang2023impactofprotein pages 4-5). Instead, NAA35 functions as the central assembly hub that holds the NatC complex together and creates the appropriate environment for catalysis (grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 9-10).

The heterotrimeric NatC complex exhibits a unique architecture that is strikingly different from other NAT complexes, primarily due to the specialized structure and interactions of NAA35 (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3). NAA35 forms extensive interactions with both other subunits: it wraps around almost the entire circumference of the small NAA38 subunit (burying approximately 1,970 Å²) and encloses about three-quarters of the NAA30 catalytic subunit in a more condensed, ring-like structure (burying approximately 1,890 Å²) (grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 2-3). This highly intertwined quaternary assembly generates a central tunnel and peptide-binding groove that are essential for substrate recognition (grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 2-3).

Substrate Recognition and Specificity

NatC exhibits specificity for proteins that retain their initiator methionine followed by a hydrophobic or amphipathic amino acid (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 1-2, damme2023expandedinvivo pages 1-2). The canonical substrate classes include N-termini starting with ML (methionine-leucine), MF (methionine-phenylalanine), MI (methionine-isoleucine), and MW (methionine-tryptophan) (grunwald2020divergentarchitectureof pages 1-2, damme2023expandedinvivo pages 1-2). Expanded proteome-wide profiling in yeast has revealed additional substrate types including MY, MK, MM, MA, MV, and MS, though some of these may show redundancy with other NATs (damme2023expandedinvivo pages 1-2).

Importantly, the peptide-binding site of NatC is formed at the interface between NAA30 and NAA35, with both subunits contributing to substrate recognition (grunwald2020divergentarchitectureof pages 3-4, grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 6-7). Structural studies revealed that the first four amino acids of cognate substrates are recognized at this NAA30-NAA35 interface, with positions 3 and 4 also contributing significantly to binding affinity and catalytic efficiency (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 6-7, grunwald2020divergentarchitectureof pages 9-10). This deep, confined peptide-binding pocket created by the NAA30-NAA35 interface explains NatC's preference for hydrophobic N-termini and distinguishes it from the more open binding sites of other NATs (grunwald2020divergentarchitectureof pages 9-10).

Requirement of All Three Subunits for Activity

All three NatC subunits—NAA30, NAA35, and NAA38—are essential for full enzymatic activity in vivo (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2). Deletion of any subunit in yeast results in complete loss of NatC-mediated acetylation for model substrates (grunwald2020divergentarchitectureof pages 9-10). While NAA30 contains the catalytic residues and NAA35 provides the structural framework, NAA38 also plays a critical stabilizing role; deletion of NAA38 reduced the catalytic turnover number (kcat) to only 6% of wild-type activity (grunwald2020divergentarchitectureof pages 7-8). NAA38 appears to stabilize the N-terminus of NAA35, which forms part of the extended peptide-binding pocket (grunwald2020divergentarchitectureof pages 9-10).

Cellular Localization and Ribosome Association

Ribosome-Associated Co-Translational Activity

NAA35, as part of the NatC complex, localizes to ribosomes where it functions co-translationally (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 1-2, grunwald2020divergentarchitectureof pages 8-9, aksnes2019cotranslationalposttranslationaland pages 4-5). The major NATs, including NatC, are associated with mono- and polyribosomes and act on nascent polypeptide chains as they emerge from the ribosomal exit tunnel (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 8-9). This co-translational mode of action distinguishes the ribosome-associated NATs from post-translational acetyltransferases like NatF and NatH (aksnes2023natsata pages 1-2, aksnes2019cotranslationalposttranslationaland pages 4-5).

The NAA35 Tip Region: Critical for Ribosome Binding

A distinctive structural feature of NAA35 is an elongated extension termed the "NAA35 tip region," which protrudes approximately 30 Å from the main body of the NatC complex (grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 8-9). This tip is formed primarily by helices α20 and α21 near the C-terminus of NAA35 (grunwald2020divergentarchitectureof pages 2-3). Structural modeling and biochemical co-sedimentation assays demonstrated that this electropositive tip region directly contacts ribosomal RNA and is essential for the stable association of NatC with ribosomes (grunwald2020divergentarchitectureof pages 8-9, grunwald2020divergentarchitectureof pages 10-11).

Mutagenesis studies identified several distinct electropositive regions (EPRs) on the NatC surface, with EPR2 located on the NAA35 tip containing 11 positively charged residues (grunwald2020divergentarchitectureof pages 8-9). Alanine substitution of four lysine residues (K500, K501, K503, K504) in the Tip1 mutant significantly reduced ribosome binding without substantially affecting intrinsic catalytic activity, confirming the tip's dedicated role in ribosome recruitment (grunwald2020divergentarchitectureof pages 8-9). Importantly, the NAA38 subunit is not required for ribosome association, as the NAA35-NAA30 heterodimer could still associate with ribosomes (grunwald2020divergentarchitectureof pages 8-9).

Structural and Mechanistic Insights

Crystal Structure and Unique Architecture

The crystal structure of the Saccharomyces cerevisiae NatC complex was solved to 2.40-2.45 Å resolution, providing detailed insights into the molecular organization of the complex (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3). NAA35 adopts a predominantly α-helical structure with short β-strands in the N- and C-terminal regions (grunwald2020divergentarchitectureof pages 2-3). Notably, database searches revealed no close structural homologs for NAA35 in the Protein Data Bank, indicating that it has evolved a unique, specialized architecture for its role in the NatC complex (grunwald2020divergentarchitectureof pages 2-3, grunwald2020divergentarchitectureof pages 9-10).

The architecture of NatC differs markedly from the heterodimeric NatA and NatB complexes (grunwald2020divergentarchitectureof pages 4-5). While the auxiliary subunits of NatA (NAA15) and NatB (NAA25) primarily engulf the N-terminal portions of their catalytic subunits, NAA35 wraps around both the N-terminal and C-terminal halves of NAA30, creating a more extensive and intertwined structure (grunwald2020divergentarchitectureof pages 4-5). Furthermore, the β6-β7 loop of NAA30, which is critical for substrate binding, makes direct contact with NAA35 in the NatC complex—a feature not observed in NatA or NatB (grunwald2020divergentarchitectureof pages 4-5).

Substrate-Induced Conformational Changes

Structural studies with cofactor and ligand-bound NatC complexes revealed dynamic, sequence-specific conformational changes upon substrate binding (grunwald2020divergentarchitectureof pages 6-7, grunwald2020divergentarchitectureof pages 7-8). Binding of substrate peptides, particularly those with optimal sequences like the viral Gag peptide (MLRFV), induced large conformational rearrangements in the β6-β7 loop of NAA30 and movement of the α1-α2 loop, resulting in constriction of the central tunnel (grunwald2020divergentarchitectureof pages 6-7, grunwald2020divergentarchitectureof pages 7-8). These ligand-induced conformational changes are essential for efficient catalysis and demonstrate the structural plasticity of the NatC active site (grunwald2020divergentarchitectureof pages 6-7).

Catalytic Mechanism

Although NAA35 does not directly participate in catalysis, it supports the catalytic mechanism by maintaining the proper positioning of active site residues in NAA30 (grunwald2020divergentarchitectureof pages 7-8, grunwald2020divergentarchitectureof pages 9-10). The proposed catalytic mechanism involves key residues in NAA30 including Glu118 (general base), Tyr80 (coordinating a catalytic water), and Tyr130 (general acid) (grunwald2020divergentarchitectureof pages 7-8). NAA35's role is primarily architectural, ensuring that the catalytic machinery is properly organized and that substrates can access the active site efficiently (grunwald2020divergentarchitectureof pages 7-8, grunwald2020divergentarchitectureof pages 9-10).

Evolutionary Conservation

The NatC complex and its constituent subunits, including NAA35, are evolutionarily conserved from yeast to humans (grunwald2020divergentarchitectureof pages 1-2, damme2023expandedinvivo pages 1-2). Studies have demonstrated functional conservation, with human NAA30 able to rescue yeast deletion mutant phenotypes and partially restore the yeast NatC Nt-acetylome (damme2023expandedinvivo pages 1-2). This conservation underscores the fundamental biological importance of NatC-mediated acetylation across eukaryotes (damme2023expandedinvivo pages 1-2).

Biological Pathways and Cellular Functions

NAA35, through its role in the NatC complex, participates in multiple critical cellular pathways and processes. The functional impact of NatC extends far beyond simple protein modification, influencing protein stability, localization, complex formation, and quality control.

Protein Quality Control and the Arg/N-Degron Pathway

One of the most significant recent discoveries is that NatC-mediated N-terminal acetylation serves as a protective mechanism against protein degradation (varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2). Genome-wide CRISPR knockout screens in human cells revealed strong negative genetic interactions between NatC subunits (including NAA35) and components of the Arg/N-degron pathway, particularly the E3 ubiquitin ligase complex UBR4-KCMF1 (varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2, varland2023nterminalacetylationshields pages 3-4).

Both the UBR4-KCMF1 ubiquitin ligase complex and the NatC acetyltransferase recognize proteins bearing an unacetylated N-terminal methionine followed by a hydrophobic residue (varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2). When NatC is absent, these proteins remain unacetylated and become targets for UBR4-KCMF1-mediated ubiquitination and proteasomal degradation (varland2023nterminalacetylationshields pages 1-2). Conversely, NatC-mediated acetylation shields these N-termini, preventing recognition by the Arg/N-degron pathway and thereby stabilizing the proteins (varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2). This interplay between NatC and the UBR4-KCMF1 pathway represents a fundamental mechanism of protein quality control and proteostasis regulation (varland2023nterminalacetylationshields pages 1-2).

Subcellular Protein Targeting and Vesicle Trafficking

NatC-mediated acetylation is crucial for the correct subcellular targeting of numerous proteins, particularly those involved in Golgi and vesicle trafficking (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 1-2, varland2023nterminalacetylationshields pages 3-4). Genetic interaction screens with NAA35 knockout cells showed enrichment for genes involved in Golgi vesicle transport, endosomal transport, and virion assembly (varland2023nterminalacetylationshields pages 2-3, varland2023nterminalacetylationshields pages 3-4).

Well-characterized examples include the small GTPases ARFRP1 (Arl3 in yeast) and ARL8B, whose acetylation by NatC is essential for their proper localization (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 1-2, aksnes2019cotranslationalposttranslationaland pages 4-5). ARFRP1/Arl3 requires NatC-mediated acetylation of its N-terminal methionine for targeting to the trans-Golgi network, a process mediated by interaction between the acetylated N-terminus and the membrane protein SYS1 (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 1-2). Similarly, ARL8B depends on NatC acetylation for correct targeting to lysosomes (varland2023nterminalacetylationshields pages 1-2). Loss of NatC leads to mislocalization of these proteins and disruption of organelle function (grunwald2020divergentarchitectureof pages 1-2, varland2023nterminalacetylationshields pages 2-3).

Neddylation Pathway and Cullin Regulation

NatC plays an important role in the neddylation pathway by acetylating the NEDD8-conjugating enzymes UBE2M (UBC12 in yeast) and UBE2F (varland2023nterminalacetylationshields pages 1-2, aksnes2019cotranslationalposttranslationaland pages 4-5). The acetylated N-terminus of UBE2M interacts with a hydrophobic pocket in the E3 ligase adaptor DCN1 (DCUN1D1 in mammals), significantly enhancing the affinity of this interaction and promoting efficient cullin neddylation (aksnes2019cotranslationalposttranslationaland pages 4-5). Cullin neddylation is essential for the activation of cullin-RING E3 ubiquitin ligases, which regulate numerous cellular processes including cell cycle progression and protein degradation (varland2023nterminalacetylationshields pages 1-2). Thus, NAA35, through the NatC complex, indirectly influences the ubiquitin-proteasome system via this acetylation-dependent mechanism.

Mitochondrial Biology

NatC has been implicated in mitochondrial protein biology through multiple lines of evidence (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2, nashed2023functionalmappingof pages 1-3). In yeast, deletion of NatC subunits results in reduced growth on non-fermentable carbon sources (such as glycerol), suggesting defects in mitochondrial function (grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2). In human cells, depletion of NAA30 leads to reduced expression of mitochondrial proteins, loss of mitochondrial membrane potential, and mitochondrial fragmentation (grunwald2020divergentarchitectureof pages 2-3, damme2023expandedinvivo pages 1-2).

Recent functional genomics work in yeast identified that mitochondrial targeting sequences (MTS) show a strong over-representation of hydrophobic residues at position 2, precisely matching the substrate specificity of NatC (nashed2023functionalmappingof pages 1-3). Co-translational purification of NatC-associated ribosomes confirmed that mitochondrial precursor proteins are indeed targeted by NatC during translation (nashed2023functionalmappingof pages 1-3). Systematic mutagenesis of position 2 in a model mitochondrial protein confirmed that this residue is critical for efficient mitochondrial import, providing a molecular explanation for the mitochondrial defects observed in NatC-depleted cells (nashed2023functionalmappingof pages 1-3).

Development, Aging, and Organismal Phenotypes

Loss of NatC function has profound effects on organismal development, aging, and lifespan across multiple model systems (grunwald2020divergentarchitectureof pages 1-2, grunwald2020divergentarchitectureof pages 2-3, varland2023nterminalacetylationshields pages 1-2). In zebrafish, knockout of NAA30 or NAA35 led to decreased cell proliferation, increased apoptosis, poor blood vessel formation, and embryonic lethality (grunwald2020divergentarchitectureof pages 1-2).

In Drosophila melanogaster, loss of NatC was associated with male sterility, reduced longevity, and age-dependent loss of motility due to developmental muscle defects (varland2023nterminalacetylationshields pages 1-2). Remarkably, muscle-specific overexpression of UbcE2M (the fly ortholog of UBE2M), one of the key proteins targeted for degradation in NatC knockout conditions, was sufficient to suppress many of the defects caused by NatC deletion, including motility and longevity phenotypes (varland2023nterminalacetylationshields pages 1-2). This finding demonstrates that NatC-mediated protection of specific substrate proteins from degradation has direct physiological consequences for healthy aging and tissue function.

In yeast, NatC deletion affects stress responses, with all three subunit mutants showing osmotic sensitivity and reduced growth under high salt stress (damme2023expandedinvivo pages 1-2). Additionally, NatC has been implicated in starvation-induced nuclear-to-cytosolic relocalization of the proteasome, an age-dependent process (damme2023expandedinvivo pages 1-2).

Cancer and Disease Relevance

While direct disease associations for NAA35 remain limited compared to other NAT subunits, emerging evidence suggests potential roles in human pathology (grunwald2020divergentarchitectureof pages 1-2, aksnes2023natsata pages 1-2). The catalytic subunit NAA30 has been shown to be upregulated in glioblastoma, and knockdown of NAA30 in glioblastoma-initiating cells reduced their viability, sphere-forming ability, and hypoxia tolerance (grunwald2020divergentarchitectureof pages 1-2). Mice transplanted with NAA30-depleted glioblastoma cells showed prolonged survival, indicating that NatC may serve as a therapeutic target in certain cancers (grunwald2020divergentarchitectureof pages 1-2).

A potentially pathogenic de novo variant in NAA35 has been identified in patients with cerebral palsy, a heterogeneous group of disorders affecting movement and posture, though the causal relationship requires further validation (grunwald2020divergentarchitectureof pages 1-2). Given the essential nature of NatC and its broad effects on protein homeostasis, it is plausible that NAA35 variants could contribute to developmental or neurological disorders, but more research is needed to establish definitive disease links.

Summary and Perspective

NAA35 functions as the large auxiliary subunit and central scaffold of the evolutionarily conserved NatC N-terminal acetyltransferase complex. While NAA35 does not possess intrinsic catalytic activity, it is absolutely essential for NatC function. NAA35's primary roles include: (1) organizing the heterotrimeric architecture by wrapping around both NAA30 and NAA38, (2) contributing residues to the substrate-binding interface with NAA30 that determines specificity for methionine-hydrophobic N-termini, and (3) mediating ribosome association through a specialized electropositive tip region.

NAA35 enables NatC to function co-translationally at the ribosomal exit tunnel, acetylating nascent polypeptides with N-terminal sequences beginning with Met followed by hydrophobic residues. This acetylation modification has profound biological consequences, including protection of proteins from degradation by the Arg/N-degron pathway, facilitation of subcellular targeting to organelles such as the Golgi and mitochondria, and enhancement of neddylation pathway activity.

The structural biology of NAA35 reveals a unique, specialized architecture with no close homologs, reflecting its evolved function in coordinating NatC assembly and ribosome binding. Recent advances in understanding the NatC-UBR4-KCMF1 interplay have revealed N-terminal acetylation as a critical mechanism of protein quality control. The conservation of NAA35 and NatC from yeast to humans, combined with emerging disease associations and the complex's involvement in aging and development, underscores the fundamental importance of this auxiliary subunit in cellular physiology.

Future research directions include elucidating additional NatC substrates and their specific functional outcomes, understanding how NatC activity is regulated in different cellular contexts, and exploring the therapeutic potential of modulating NatC function in diseases such as cancer and developmental disorders.

References

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(grunwald2020divergentarchitectureof pages 8-9): Stephan Grunwald, Linus V. M. Hopf, Tobias Bock-Bierbaum, Ciara C. M. Lally, Christian M. T. Spahn, and Oliver Daumke. Divergent architecture of the heterotrimeric natc complex explains n-terminal acetylation of cognate substrates. Nature Communications, Nov 2020. URL: https://doi.org/10.1038/s41467-020-19321-8, doi:10.1038/s41467-020-19321-8. This article has 39 citations and is from a highest quality peer-reviewed journal.
(grunwald2020divergentarchitectureof pages 6-7): Stephan Grunwald, Linus V. M. Hopf, Tobias Bock-Bierbaum, Ciara C. M. Lally, Christian M. T. Spahn, and Oliver Daumke. Divergent architecture of the heterotrimeric natc complex explains n-terminal acetylation of cognate substrates. Nature Communications, Nov 2020. URL: https://doi.org/10.1038/s41467-020-19321-8, doi:10.1038/s41467-020-19321-8. This article has 39 citations and is from a highest quality peer-reviewed journal.
(nashed2023functionalmappingof pages 1-3): Salomé Nashed, Houssam El Barbry, Médine Benchouaia, Angélie Dijoux-Maréchal, T. Delaveau, Nadia Ruiz-Gutierrez, Lucie Gaulier, D. Tribouillard-Tanvier, Guillaume Chevreux, S. Le Crom, Benoît Palancade, F. Devaux, É. Laine, and Mathilde Garcia. Functional mapping of n-terminal residues in the yeast proteome uncovers novel determinants for mitochondrial protein import. PLOS Genetics, Aug 2023. URL: https://doi.org/10.1101/2022.08.19.504527, doi:10.1101/2022.08.19.504527. This article has 5 citations and is from a domain leading peer-reviewed journal.
(varland2023nterminalacetylationshields pages 3-4): Sylvia Varland, Rui Duarte Silva, Ine Kjosås, Alexandra Faustino, Annelies Bogaert, Maximilian Billmann, Hadi Boukhatmi, Barbara Kellen, Michael Costanzo, Adrian Drazic, Camilla Osberg, Katherine Chan, Xiang Zhang, Amy Hin Yan Tong, Simonetta Andreazza, Juliette J. Lee, Lyudmila Nedyalkova, Matej Ušaj, Alexander J. Whitworth, Brenda J. Andrews, Jason Moffat, Chad L. Myers, Kris Gevaert, Charles Boone, Rui Gonçalo Martinho, and Thomas Arnesen. N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity. Nature Communications, Oct 2023. URL: https://doi.org/10.1038/s41467-023-42342-y, doi:10.1038/s41467-023-42342-y. This article has 96 citations and is from a highest quality peer-reviewed journal.
(aksnes2019cotranslationalposttranslationaland pages 4-5): Henriette Aksnes, Rasmus Ree, and Thomas Arnesen. Co-translational, post-translational, and non-catalytic roles of n-terminal acetyltransferases. Molecular cell, 73 6:1097-1114, Mar 2019. URL: https://doi.org/10.1016/j.molcel.2019.02.007, doi:10.1016/j.molcel.2019.02.007. This article has 277 citations and is from a highest quality peer-reviewed journal.
(grunwald2020divergentarchitectureof pages 10-11): Stephan Grunwald, Linus V. M. Hopf, Tobias Bock-Bierbaum, Ciara C. M. Lally, Christian M. T. Spahn, and Oliver Daumke. Divergent architecture of the heterotrimeric natc complex explains n-terminal acetylation of cognate substrates. Nature Communications, Nov 2020. URL: https://doi.org/10.1038/s41467-020-19321-8, doi:10.1038/s41467-020-19321-8. This article has 39 citations and is from a highest quality peer-reviewed journal.
(varland2023nterminalacetylationshields pages 2-3): Sylvia Varland, Rui Duarte Silva, Ine Kjosås, Alexandra Faustino, Annelies Bogaert, Maximilian Billmann, Hadi Boukhatmi, Barbara Kellen, Michael Costanzo, Adrian Drazic, Camilla Osberg, Katherine Chan, Xiang Zhang, Amy Hin Yan Tong, Simonetta Andreazza, Juliette J. Lee, Lyudmila Nedyalkova, Matej Ušaj, Alexander J. Whitworth, Brenda J. Andrews, Jason Moffat, Chad L. Myers, Kris Gevaert, Charles Boone, Rui Gonçalo Martinho, and Thomas Arnesen. N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity. Nature Communications, Oct 2023. URL: https://doi.org/10.1038/s41467-023-42342-y, doi:10.1038/s41467-023-42342-y. This article has 96 citations and is from a highest quality peer-reviewed journal.
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Artifacts

Edison artifact artifact-00

Citations

aksnes2023natsata pages 1-2
damme2023expandedinvivo pages 1-2
grunwald2020divergentarchitectureof pages 9-10
grunwald2020divergentarchitectureof pages 7-8
grunwald2020divergentarchitectureof pages 2-3
grunwald2020divergentarchitectureof pages 8-9
grunwald2020divergentarchitectureof pages 4-5
grunwald2020divergentarchitectureof pages 6-7
varland2023nterminalacetylationshields pages 1-2
aksnes2019cotranslationalposttranslationaland pages 4-5
nashed2023functionalmappingof pages 1-3
grunwald2020divergentarchitectureof pages 1-2
chang2023impactofprotein pages 4-5
grunwald2020divergentarchitectureof pages 3-4
varland2023nterminalacetylationshields pages 3-4
grunwald2020divergentarchitectureof pages 10-11
varland2023nterminalacetylationshields pages 2-3
https://doi.org/10.1242/jcs.260766,
https://doi.org/10.1038/s41467-020-19321-8,
https://doi.org/10.1016/j.jbc.2022.102824,
https://doi.org/10.1038/s41467-023-42342-y,
https://doi.org/10.3390/life13071613,
https://doi.org/10.1101/2022.08.19.504527,
https://doi.org/10.1016/j.molcel.2019.02.007,

📚 Additional Documentation

Notes

(NAA35-notes.md)

NAA35 (N-alpha-acetyltransferase 35, NatC auxiliary subunit / MAK10 / EGAP) notes

Identity

UniProt Q5VZE5; HGNC; aka MAK10, EGAP (embryonic growth-associated protein homolog). 725 aa.
AUXILIARY (non-catalytic) subunit of the human NatC complex (NatC = NAA30 catalytic + NAA35 + NAA38). MAK10 family.

Function

Auxiliary component of NatC; NatC acetylates N-terminal Met before bulky/hydrophobic residues.
[UniProt FUNCTION "Auxillary component of the N-terminal acetyltransferase C (NatC) complex which catalyzes acetylation of N-terminal methionine residues"]
NatC N-terminal acetylation protects substrates from N-end-rule ubiquitination/degradation. PMID:37891180
Knockdown of NatC subunits -> p53-dependent apoptosis. PMID:19398576
EGAP (mouse ortholog) implicated in smooth-muscle-cell proliferation / embryonic vascular development. [PMID:16484612 title "Embryonic growth-associated protein is one subunit of a novel N-terminal acetyltransferase complex essential for embryonic vascular development"] -> origin of GO:0048659 (ISS/IEA from mouse).

Complex / structure

Component of NatC (NAA35 + NAA38 + NAA30). [UniProt SUBUNIT]
Cryo-EM structures of human/Candida NatC (PDB 7MX2, 7RB3) show NAA35/Mak10 as the large scaffold subunit.

Annotation notes

NO catalytic acetyltransferase MF on NAA35 in GOA (correct — it is non-catalytic). Core CC = NatC complex.
GO:0031417 NatC complex (IBA/IEA/IPI/IDA) — core CC, accept.
protein binding IPI: PMID:19398576 WITH NAA30 (Q147X3) and NAA38 (Q9BRA0) = real complex partners -> KEEP_AS_NON_CORE (subsumed by NatC). PMID:33961781 same partners. PMID:40205054 WITH NAA30. PMID:32296183 (HuRI binary screen) WITH TRIM7 (Q9C029) = isolated HT interaction, unrelated -> MARK_AS_OVER_ANNOTATED.
negative regulation of apoptotic process (IBA, IMP PMID:19398576): NatC KD -> p53-dependent apoptosis, i.e. NatC normally suppresses apoptosis. Downstream BP of complex function -> KEEP_AS_NON_CORE.
smooth muscle cell proliferation (ISS/IEA from mouse EGAP): peripheral developmental/vascular role, organism-specific -> KEEP_AS_NON_CORE.
cytoplasm/cytosol localizations (IDA/NAS/ISS/IEA) consistent -> accept; cytoplasm is primary.

Pn Notes

(NAA35-pn-notes.md)

NAA35 PN Consistency Notes

Generated: 2026-06-18
Project: PROTEOSTASIS
Scope: PN consistency rereview against local AIGR review and available deep-research artifacts
UniProt: Q5VZE5
AIGR review status: COMPLETE
Review batch: proteostasis-batch-2026-06-07c
Batch change status: added

Source Files Checked

AIGR review YAML: present - genes/human/NAA35/NAA35-ai-review.yaml
AIGR review HTML: present - genes/human/NAA35/NAA35-ai-review.html
Gene notes: present - genes/human/NAA35/NAA35-notes.md
GOA TSV: present - genes/human/NAA35/NAA35-goa.tsv
UniProt record: present - genes/human/NAA35/NAA35-uniprot.txt
PN dossier: projects/PROTEOSTASIS/reports/phase1_dossiers/NAA35.md
PN consistency section: projects/PROTEOSTASIS/reports/phase1_dossiers/_sections/NAA35.md
PN projection report: projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv
PN mapping audit: projects/PROTEOSTASIS/reports/pn_mapping_audit/current_mapping_scrutiny.tsv

Deep Research Files

No *-deep-research*.md file found in this gene directory.

AIGR Review Snapshot

Description: NAA35 (N-alpha-acetyltransferase 35; also MAK10, EGAP) is the large non-catalytic auxiliary/scaffold subunit of the human NatC N-terminal acetyltransferase complex (NatC = NAA30 catalytic + NAA35 + NAA38). It does not itself catalyze acetyl transfer; instead it scaffolds the complex and is required for NatC function and integrity. NatC co-translationally acetylates the alpha-amino group of N-terminal methionine residues retained in front of bulky/hydrophobic residues, a modification that shields substrates from N-degron-mediated ubiquitination and degradation. NAA35 is predominantly cytoplasmic and ribosome-associated. Loss of NatC subunits triggers p53-dependent apoptosis, and the mouse ortholog (EGAP) has been linked to smooth-muscle-cell proliferation and embryonic vascular development.
Existing/core annotation action counts: ACCEPT: 10; KEEP_AS_NON_CORE: 8; NEW: 1

PN Consistency Summary

Consistency: Strong. All three sources agree NAA35 (MAK10/EGAP) is the large non-catalytic auxiliary/scaffold subunit of NatC; no catalytic MF is asserted (correct). PN-node mapping (NatC complex CC; Nt-acetylation BP) is consistent with the auxiliary role.
PN story / NEW pressure: PN projects BP GO:0006474 (verified real; confirmed absent from NAA35 GOA). For a non-catalytic scaffold an involved_in BP of N-terminal acetylation is defensible (it is part of the complex that performs the process), and complements the review's CC-only core. Conclusion: ADD GO:0006474 (involved_in) is reasonable; the catalytic MF must NOT be added (NAA35 is non-catalytic). Not an over-reach.
Evidence alignment: Concordant. Review/notes use PMID:19398576 (NatC; hMak10 auxiliary; IDA GO:0031417, IMP GO:0043066), PMID:37891180, plus mouse EGAP origin (PMID:16484612, cited in notes) for the smooth-muscle/vascular ISS/IEA. PN row carries no titles. No divergence.
Verdict: Consistent, high-quality. Internal note vs YAML mismatch: notes say PMID:32296183 (TRIM7) protein-binding should be MARK_AS_OVER_ANNOTATED, but YAML uses KEEP_AS_NON_CORE (minor, defensible either way). Recommended edits: Add BP GO:0006474 (involved_in, auxiliary subunit of the acetylating complex) to NAA35 review [YAML]; optionally reconcile PMID:32296183 action with notes (KEEP_AS_NON_CORE vs MARK_AS_OVER_ANNOTATED) [YAML].

Full Consistency Review

UniProt: Q5VZE5 · batch: proteostasis-batch-2026-06-07c · review status: COMPLETE
PN placement: Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide|NatC complex component ; PN-node mapping: subtype mapped→GO:0031417 NatC complex (ok_for_propagation); type mapped→GO:0006474 N-terminal protein amino acid acetylation (ok_for_propagation, new_to_goa)
Consistency: Strong. All three sources agree NAA35 (MAK10/EGAP) is the large non-catalytic auxiliary/scaffold subunit of NatC; no catalytic MF is asserted (correct). PN-node mapping (NatC complex CC; Nt-acetylation BP) is consistent with the auxiliary role.
PN story / NEW pressure: PN projects BP GO:0006474 (verified real; confirmed absent from NAA35 GOA). For a non-catalytic scaffold an involved_in BP of N-terminal acetylation is defensible (it is part of the complex that performs the process), and complements the review's CC-only core. Conclusion: ADD GO:0006474 (involved_in) is reasonable; the catalytic MF must NOT be added (NAA35 is non-catalytic). Not an over-reach.
Mapping strategy: Correct. Subtype→NatC complex exact CC is the safe target for an auxiliary subunit; BP propagated at type level. No node-mapping change warranted.
Evidence alignment: Concordant. Review/notes use PMID:19398576 (NatC; hMak10 auxiliary; IDA GO:0031417, IMP GO:0043066), PMID:37891180, plus mouse EGAP origin (PMID:16484612, cited in notes) for the smooth-muscle/vascular ISS/IEA. PN row carries no titles. No divergence.
Verdict: Consistent, high-quality. Internal note vs YAML mismatch: notes say PMID:32296183 (TRIM7) protein-binding should be MARK_AS_OVER_ANNOTATED, but YAML uses KEEP_AS_NON_CORE (minor, defensible either way). Recommended edits: Add BP GO:0006474 (involved_in, auxiliary subunit of the acetylating complex) to NAA35 review [YAML]; optionally reconcile PMID:32296183 action with notes (KEEP_AS_NON_CORE vs MARK_AS_OVER_ANNOTATED) [YAML].
2026-06-18 follow-up: Implemented the high-confidence YAML edit: added GO:0006474 N-terminal protein amino acid acetylation as a NEW BP recommendation and core process for the NatC auxiliary subunit, using IC to reflect inference from NatC complex membership rather than direct catalytic activity. The optional protein-binding action-style reconciliation remains separate.

PN Dossier Context

review_batch: proteostasis-batch-2026-06-07c
review_yaml: genes/human/NAA35/NAA35-ai-review.yaml
PN workbook rows: 1

PN row 1: Translation | Cytosolic translation | Nascent peptide husbandry | N-terminal acetylation of nascent peptide | NatC complex component

UniProt: Q5VZE5
In branches: TR
PN-node mapping records (path + ancestors):
- [subtype] Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide|NatC complex component
  status=mapped scope=ok_for_propagation_to_go GO=[GO:0031417 NatC complex]
  rationale: Exact cellular-component match: members are subunits of the NatC N-terminal acetyltransferase complex. Complements the parent BP mapping with the complex-membership CC term.
- [type] Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide
  status=mapped scope=ok_for_propagation_to_go GO=[GO:0006474 N-terminal protein amino acid acetylation]
  rationale: This PN type denotes N-terminal acetyltransferase machinery acting on nascent peptides. The GO N-terminal acetylation process is the direct target.
- [group] Translation|Cytosolic translation|Nascent peptide husbandry
  status=no_mapping scope= GO=[]
  rationale: Reviewed as a broad PN category rather than a single GO class. The member genes span multiple activities, complexes, or contexts, so direct propagation from this node would overstate the shared biology.
- [class] Translation|Cytosolic translation
  status=context_only scope=too_broad_to_propagate GO=[GO:0002181 cytoplasmic translation]
  rationale: The PN class Cytosolic translation is centered on the cytoplasmic translation apparatus and process, but it also houses supporting machinery such as ribosome biogenesis factors. The GO process term is a useful high-level label for the class, but propagating it to all members would over-annotate genes whose PN placement is through assembly or maturation context rather than core cytoplasmic translation.
- [branch] Translation
  status=context_only scope=too_broad_to_propagate GO=[GO:0006412 translation]
  rationale: The PN Translation branch is organized around the translation apparatus and immediately associated cotranslational quality-control systems. GO translation is the closest high-level process label, but the PN branch also contains adjacent machinery such as ribosome biogenesis and nascent-chain handling. Keeping this relationship is useful for interpretation, but it is too broad to project safely onto every member.

Projected GO annotations (1)

GO:0006474 N-terminal protein amino acid acetylation | scope=ok_for_propagation_to_go | goa_status=new_to_goa | from=Translation|Cytosolic translation|Nascent peptide husbandry|N-terminal acetylation of nascent peptide

Note

This file is generated from the current PROTEOSTASIS phase-1 dossier and local gene-review artifacts. Edit the source review, PN mapping, or dossier rather than this generated note when correcting the underlying curation.

📄 View Raw YAML

id: Q5VZE5
gene_symbol: NAA35
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: NAA35 (N-alpha-acetyltransferase 35; also MAK10, EGAP) is the large non-catalytic auxiliary/scaffold subunit of the human NatC N-terminal acetyltransferase complex (NatC = NAA30 catalytic + NAA35 + NAA38). It does not itself catalyze acetyl transfer; instead it scaffolds the complex and is required for NatC function and integrity. NatC co-translationally acetylates the alpha-amino group of N-terminal methionine residues retained in front of bulky/hydrophobic residues, a modification that shields substrates from N-degron-mediated ubiquitination and degradation. NAA35 is predominantly cytoplasmic and ribosome-associated. Loss of NatC subunits triggers p53-dependent apoptosis, and the mouse ortholog (EGAP) has been linked to smooth-muscle-cell proliferation and embryonic vascular development.
alternative_products:
- name: '1'
  id: Q5VZE5-1
- name: '2'
  id: Q5VZE5-2
  sequence_note: VSP_056098, VSP_056099
existing_annotations:
- term:
    id: GO:0031417
    label: NatC complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: NAA35 is a constitutive auxiliary subunit of the NatC complex; phylogenetic inference across MAK10 orthologs supports this membership, which is also directly demonstrated. Structural work (Grunwald 2020) shows NAA35 is the central scaffold that wraps around both NAA30 and NAA38 to hold the heterotrimer together.
    action: ACCEPT
    reason: NatC complex membership is the defining cellular component of NAA35 and is well supported by phylogenetic and direct experimental evidence.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
    - reference_id: file:human/NAA35/NAA35-deep-research-falcon.md
      supporting_text: NAA35's primary role is to serve as the central assembly scaffold that organizes the NatC complex architecture and mediates its interaction with ribosomes, thereby enabling co-translational N-terminal acetylation of specific substrate proteins
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Knockdown of NatC subunits (including NAA35) induces p53-dependent apoptosis, implying that NatC activity normally suppresses apoptosis. This is a downstream biological-process consequence of NatC-mediated N-terminal acetylation, not a direct molecular activity of NAA35.
    action: KEEP_AS_NON_CORE
    reason: Plausible process annotation derived from the apoptotic phenotype of NatC depletion; indirect and downstream of the complex's core acetyltransferase activity.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Involved in regulation of apoptosis and proliferation of smooth muscle cells
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Electronic annotation of cytoplasmic localization, consistent with the experimentally documented cytoplasmic site of NatC.
    action: ACCEPT
    reason: Cytoplasm is the principal, experimentally supported compartment of NatC.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- term:
    id: GO:0031417
    label: NatC complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: part_of
  review:
    summary: InterPro-based electronic annotation of NatC complex membership, redundant with and consistent with stronger experimental evidence.
    action: ACCEPT
    reason: Correct and well-corroborated NatC complex membership.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19398576
  qualifier: enables
  review:
    summary: IntAct interactions with NAA30 (Q147X3) and NAA38 (Q9BRA0), the other NatC subunits. The bare protein binding term is uninformative; the relevant interaction is NatC complex assembly.
    action: KEEP_AS_NON_CORE
    reason: Records genuine intra-complex interactions but the uninformative GO:0005515 term is non-core; NatC complex membership captures the meaningful content.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-goa.tsv
      supporting_text: GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:19398576 UniProtKB:Q147X3
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: Binary yeast two-hybrid interactome (HuRI) interaction with TRIM7 (Q9C029), an E3 ligase unrelated to NatC function. An isolated high-throughput interaction that does not inform NAA35's core role.
    action: KEEP_AS_NON_CORE
    reason: Bare protein binding from a single high-throughput binary screen with a partner (TRIM7) outside the NatC complex; uninformative and not part of the core function.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-goa.tsv
      supporting_text: GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:32296183 UniProtKB:Q9C029
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: BioPlex interactome interactions with NAA30 (Q147X3) and NAA38 (Q9BRA0). Uninformative bare protein binding term reflecting NatC complex assembly.
    action: KEEP_AS_NON_CORE
    reason: Real interactions with the other NatC subunits; non-core as a bare protein binding annotation, subsumed by the NatC complex term.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-goa.tsv
      supporting_text: GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:33961781 UniProtKB:Q147X3
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:40205054
  qualifier: enables
  review:
    summary: Multimodal cell-maps interactome interaction with NAA30 (Q147X3). Uninformative bare protein binding term reflecting NatC complex assembly.
    action: KEEP_AS_NON_CORE
    reason: Real interaction with the NAA30 catalytic subunit; non-core as a bare protein binding annotation, subsumed by the NatC complex term.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-goa.tsv
      supporting_text: GO:0005515 protein binding molecular_function ECO:0000353 IPI PMID:40205054 UniProtKB:Q147X3
- term:
    id: GO:0048659
    label: smooth muscle cell proliferation
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Electronic annotation transferred from the mouse ortholog (EGAP), which was implicated in smooth-muscle-cell proliferation and embryonic vascular development. This is a peripheral, organism-specific developmental role.
    action: KEEP_AS_NON_CORE
    reason: Transferred from mouse phenotype data; peripheral to NAA35's core NatC scaffold function and not a direct molecular activity.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Involved in regulation of apoptosis and proliferation of smooth muscle cells
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: Direct immunofluorescence (HPA) evidence for cytosolic localization, consistent with the cytoplasmic site of NatC.
    action: ACCEPT
    reason: IDA-supported cytosolic localization matching the cytoplasmic ribosome-associated site of NatC.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-goa.tsv
      supporting_text: GO:0005829 cytosol cellular_component ECO:0000314 IDA GO_REF:0000052
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: NAS
  original_reference_id: PMID:19398576
  qualifier: located_in
  review:
    summary: Non-traceable author statement (ComplexPortal) of cytoplasmic localization, consistent with the documented cytoplasmic site of NatC.
    action: ACCEPT
    reason: Consistent with the primary cytoplasmic localization of NatC.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- term:
    id: GO:0031417
    label: NatC complex
  evidence_type: IPI
  original_reference_id: PMID:19398576
  qualifier: part_of
  review:
    summary: ComplexPortal/IPI evidence that NAA35 is part of the NatC complex, from the study that identified the human NatC complex.
    action: ACCEPT
    reason: Direct experimental support for NatC complex membership.
    supported_by:
    - reference_id: PMID:19398576
      supporting_text: the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
- term:
    id: GO:0031417
    label: NatC complex
  evidence_type: IDA
  original_reference_id: PMID:37891180
  qualifier: part_of
  review:
    summary: Direct experimental confirmation of NatC complex membership in the protein-shielding/longevity study.
    action: ACCEPT
    reason: Well-supported NatC complex membership.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:19398576
  qualifier: located_in
  review:
    summary: Direct experimental cytoplasmic localization of NAA35, consistent with ribosome-associated NatC activity. NAA35 in particular carries the principal ribosome-binding surface of NatC (an electropositive C-terminal tip region), so its cytoplasmic localization reflects co-translational action at the ribosome.
    action: ACCEPT
    reason: Cytoplasm is the principal experimentally supported compartment of NatC.
    supported_by:
    - reference_id: PMID:19398576
      supporting_text: This complex associates with ribosomes
    - reference_id: file:human/NAA35/NAA35-deep-research-falcon.md
      supporting_text: NAA35, as part of the NatC complex, localizes to ribosomes where it functions co-translationally
- term:
    id: GO:0031417
    label: NatC complex
  evidence_type: IDA
  original_reference_id: PMID:19398576
  qualifier: part_of
  review:
    summary: Direct experimental identification of NAA35 (hMak10) as an auxiliary subunit of the human NatC complex.
    action: ACCEPT
    reason: Defining cellular component, directly demonstrated.
    supported_by:
    - reference_id: PMID:19398576
      supporting_text: the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
- term:
    id: GO:0043066
    label: negative regulation of apoptotic process
  evidence_type: IMP
  original_reference_id: PMID:19398576
  qualifier: involved_in
  review:
    summary: Mutant-phenotype evidence that NAA35 (hMak10) knockdown induces p53-dependent apoptosis, indicating NatC normally suppresses apoptosis. Downstream consequence of complex function.
    action: KEEP_AS_NON_CORE
    reason: Real phenotype-based process annotation, but indirect and downstream of NatC's core acetyltransferase activity.
    supported_by:
    - reference_id: PMID:19398576
      supporting_text: results in p53-dependent cell death
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: located_in
  review:
    summary: Sequence-similarity-based annotation of cytoplasmic localization (from mouse ortholog), consistent with the documented cytoplasmic site of NatC.
    action: ACCEPT
    reason: Consistent with the primary cytoplasmic localization of NatC; corroborated by IDA evidence.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm'
- term:
    id: GO:0048659
    label: smooth muscle cell proliferation
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Sequence-similarity-based annotation transferred from the mouse ortholog (EGAP) linked to smooth-muscle-cell proliferation and embryonic vascular development; a peripheral developmental role.
    action: KEEP_AS_NON_CORE
    reason: Transferred from mouse phenotype data; peripheral to NAA35's core NatC scaffold function.
    supported_by:
    - reference_id: file:human/NAA35/NAA35-uniprot.txt
      supporting_text: Involved in regulation of apoptosis and proliferation of smooth muscle cells
- term:
    id: GO:0006474
    label: N-terminal protein amino acid acetylation
  evidence_type: IC
  original_reference_id: PMID:19398576
  qualifier: involved_in
  review:
    summary: NAA35/hMak10 is a non-catalytic auxiliary/scaffold subunit of human NatC, the complex responsible for cotranslational N-terminal acetylation. The acetyltransferase activity resides exclusively in the catalytic NAA30 subunit (GNAT fold); NAA35 contributes the scaffold and part of the NAA30-NAA35 substrate-binding interface but does not itself transfer the acetyl group. The involved_in (process) annotation is therefore appropriate, whereas a catalytic molecular-function term for NAA35 would not be.
    action: NEW
    reason: The review captures NatC complex membership but not the BP carried out by that complex. This recommends process involvement for the auxiliary subunit while explicitly not assigning catalytic acetyltransferase MF to NAA35.
    supported_by:
    - reference_id: PMID:19398576
      supporting_text: the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
      reference_section_type: ABSTRACT
    - reference_id: PMID:19398576
      supporting_text: the human NatC complex functions in cotranslational N-terminal acetylation
      reference_section_type: ABSTRACT
    - reference_id: file:human/NAA35/NAA35-deep-research-falcon.md
      supporting_text: It is crucial to emphasize that NAA35 itself does not possess catalytic acetyltransferase activity. The catalytic function resides exclusively in the NAA30 subunit, which contains the conserved GNAT (GCN5-related N-acetyltransferase) fold
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:19398576
  title: Knockdown of human N alpha-terminal acetyltransferase complex C leads to p53-dependent apoptosis and aberrant human Arl8b localization.
  findings:
  - statement: NatC contains the catalytic subunit hMak3 (NAA30) and auxiliary subunits hMak10 (NAA35) and hMak31 (NAA38); the complex associates with ribosomes.
    reference_section_type: ABSTRACT
  - statement: Knockdown of NatC subunits results in p53-dependent cell death, indicating NatC normally suppresses apoptosis.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached publication title matches the YAML title; GOA anchors this PMID to IDA for GO:0031417 (NatC complex) and IMP for GO:0043066 (negative regulation of apoptosis) for NAA35. This is the NatC complex-characterization paper establishing NAA35 (hMak10) as an auxiliary/scaffold subunit, the gene's core function.
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
  findings: []
- id: PMID:37891180
  title: N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity.
  findings:
  - statement: NatC-mediated N-terminal acetylation shields substrate proteins from degradation, promoting protein stabilization, motility and longevity.
    reference_section_type: ABSTRACT
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Cached publication title matches the YAML title; GOA anchors this PMID to IDA for GO:0031417 (NatC complex). Supports the biological significance of the NatC complex of which NAA35 is the auxiliary subunit.
- id: PMID:40205054
  title: Multimodal cell maps as a foundation for structural and functional genomics.
  findings: []
- id: file:human/NAA35/NAA35-deep-research-falcon.md
  title: Falcon deep research report for NAA35
  findings:
  - statement: NAA35 is the large non-catalytic auxiliary/scaffold subunit of the heterotrimeric
      NatC complex (with catalytic NAA30 and small auxiliary NAA38); it organizes the
      complex architecture, contributes to the NAA30-NAA35 substrate-binding interface
      that determines Met-hydrophobic specificity, and mediates ribosome association
      via an electropositive C-terminal tip region.
  reference_review:
    relevance: HIGH
    correctness: UNVERIFIED
    review_notes: 'LLM-synthesized deep-research report. It correctly and repeatedly states
      that NAA35 does NOT itself catalyze N-terminal acetylation and that catalysis resides
      exclusively in NAA30 (GNAT fold); NAA35''s role is architectural/scaffolding and
      ribosome-binding. No mis-attribution of catalytic acetyltransferase activity to the
      auxiliary subunit was detected. Underlying primary sources (Grunwald 2020 NatC crystal
      structure; Varland 2023 N-degron shielding) are consistent with the NatC literature,
      but the specific structural/genetic-interaction claims were not independently verified
      against full text here, so correctness is left UNVERIFIED.'
core_functions:
- description: Non-catalytic auxiliary/scaffold subunit of the NatC N-terminal acetyltransferase complex, required for assembly and function of NatC, which co-translationally acetylates N-terminal methionine residues of substrates with bulky/hydrophobic second residues.
  locations:
  - id: GO:0005737
    label: cytoplasm
  supported_by:
  - reference_id: file:human/NAA35/NAA35-uniprot.txt
    supporting_text: Component of the N-terminal acetyltransferase C (NatC) complex, which is composed of NAA35, NAA38 and NAA30.
  - reference_id: PMID:19398576
    supporting_text: the catalytic subunit hMak3 and the auxiliary subunits hMak10 and hMak31
  - reference_id: file:human/NAA35/NAA35-deep-research-falcon.md
    supporting_text: NAA35's primary role is to serve as the central assembly scaffold that organizes the NatC complex architecture and mediates its interaction with ribosomes, thereby enabling co-translational N-terminal acetylation of specific substrate proteins
  in_complex:
    id: GO:0031417
    label: NatC complex
  directly_involved_in:
  - id: GO:0006474
    label: N-terminal protein amino acid acetylation
proposed_new_terms: []
suggested_questions:
- question: Does the NAA35/Mak10 scaffold mediate ribosome anchoring of NatC, and which surface contacts the ribosome versus the catalytic NAA30 subunit?
- question: Is the EGAP-associated smooth-muscle/vascular phenotype a direct consequence of altered NatC substrate acetylation, or an EGAP-specific moonlighting role?
suggested_experiments:
- description: Reconstitute NatC in vitro with and without NAA35 to test whether the auxiliary subunit is required for catalytic activity and substrate selectivity of NAA30.
- description: Cryo-EM of the NatC-ribosome complex to map the NAA35 scaffold contacts with the ribosome and the catalytic subunit.
- description: N-terminomics of NAA35-depleted human cells to define the NatC-dependent N-terminal acetylome and test whether loss of the auxiliary subunit phenocopies loss of the catalytic subunit.

NAA35

Gene Description

Existing Annotations Review

Core Functions

Non-catalytic auxiliary/scaffold subunit of the NatC N-terminal acetyltransferase complex, required for assembly and function of NatC, which co-translationally acetylates N-terminal methionine residues of substrates with bulky/hydrophobic second residues.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Comprehensive Research Report: NAA35 (N-alpha-acetyltransferase 35, NatC Auxiliary Subunit)

Overview

Primary Function and Role in the NatC Complex

The NatC Complex and N-Terminal Acetylation

NAA35 as a Structural Scaffold, Not a Catalytic Subunit

Substrate Recognition and Specificity

Requirement of All Three Subunits for Activity

Cellular Localization and Ribosome Association

Ribosome-Associated Co-Translational Activity

The NAA35 Tip Region: Critical for Ribosome Binding

Structural and Mechanistic Insights

Crystal Structure and Unique Architecture

Substrate-Induced Conformational Changes

Catalytic Mechanism

Evolutionary Conservation

Biological Pathways and Cellular Functions

Protein Quality Control and the Arg/N-Degron Pathway

Subcellular Protein Targeting and Vesicle Trafficking

Neddylation Pathway and Cullin Regulation

Mitochondrial Biology

Development, Aging, and Organismal Phenotypes

Cancer and Disease Relevance

Summary and Perspective

Artifacts

Citations

📚 Additional Documentation

Notes

NAA35 (N-alpha-acetyltransferase 35, NatC auxiliary subunit / MAK10 / EGAP) notes

Identity

Function

Complex / structure

Annotation notes

Pn Notes

NAA35 PN Consistency Notes

Source Files Checked

Deep Research Files

AIGR Review Snapshot

PN Consistency Summary

Full Consistency Review

PN Dossier Context

PN row 1: Translation | Cytosolic translation | Nascent peptide husbandry | N-terminal acetylation of nascent peptide | NatC complex component

Projected GO annotations (1)

Note

📄 View Raw YAML