| 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**. | (pqac-00000001, pqac-00000003, pqac-00000005) |
| 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. | (pqac-00000001, pqac-00000002, pqac-00000009) |
| 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. | (pqac-00000001, pqac-00000003, pqac-00000006, pqac-00000013) |
| 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**. | (pqac-00000000, pqac-00000002, pqac-00000008, pqac-00000013, pqac-00000014) |
| 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. | (pqac-00000001, pqac-00000005, pqac-00000007, pqac-00000009, pqac-00000013, pqac-00000016) |
| 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. | (pqac-00000001, pqac-00000007, pqac-00000013) |
| 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. | (pqac-00000005, pqac-00000012, pqac-00000013, pqac-00000016, pqac-00000017) |
| 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. | (pqac-00000005, pqac-00000014, pqac-00000015, pqac-00000017) |
| 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. | (pqac-00000002, pqac-00000014, pqac-00000015) |
| 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. | (pqac-00000002, pqac-00000013) |
| 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. | (pqac-00000000, pqac-00000002, pqac-00000008, pqac-00000013) |
| 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. | (pqac-00000007, pqac-00000009, pqac-00000013) |
| 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. | (pqac-00000004, pqac-00000005, pqac-00000012) |
| 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**. | (pqac-00000004, pqac-00000005, pqac-00000012, pqac-00000017) |
| 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. | (pqac-00000005, pqac-00000017) |
| 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. | (pqac-00000002, pqac-00000016) |
| 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. | (pqac-00000002, pqac-00000005) |
| 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**. | (pqac-00000001, pqac-00000003) |


*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.*