Zdhhc23 (DHHC-23; also called NIDD in rat) is a polytopic integral membrane protein S-acyltransferase of the DHHC family, with six predicted transmembrane helices and a cytoplasmic DHHC cysteine-rich domain whose cysteine C279 forms the acyl-enzyme intermediate. By orthology with human ZDHHC23 it localizes to Golgi and trans-Golgi network membranes, where it transfers palmitate from palmitoyl-CoA to cysteines of protein substrates. In mouse, genetic deletion of Zdhhc23 reduces S-acylation of the endogenous BK potassium channel alpha subunit (Kcnma1) in aortic smooth muscle cells and lowers BK current, without changing channel surface expression in this beta1-containing tissue; in cells lacking beta1, ZDHHC23-mediated acylation of the S0-S1 loop instead promotes channel exit from the TGN to the plasma membrane. Knockdown in a mouse astrocyte line reduces GFAP palmitoylation, and Zdhhc23 is upregulated in spinal astrocytes in a cancer-pain model. The rat ortholog has been reported to bind neuronal nitric oxide synthase. Zdhhc23 is expressed in brain.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000139 Golgi membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Golgi membrane is the best-supported site of ZDHHC23 activity in the orthologous clade. Reason: Mouse Zdhhc23 has six predicted transmembrane helices with the DHHC domain on the cytoplasmic side. The direct localization data come from tagged zDHHC23 in HEK293 cells (Golgi GM130 and TGN38 colocalization), and the gene sits in the ZDHHC23-specific PANTHER subfamily PTHR22883:SF475 with human ZDHHC23, so transfer is within orthologs. In mouse itself, endogenous Zdhhc23 in aortic smooth muscle cells is perinuclear, which is compatible with but does not by itself resolve a Golgi location. Golgi membrane is the appropriate granularity for a polytopic enzyme. Supporting Evidence: PMID:22399288 zDHHC23 predominantly co-localized with markers of the Golgi network (GM130, Pearson's R coefficient of 0.71 Β± 0.01, n = 15) and TGN (TGN38, Pearson's R coefficient of 0.38 Β± 0.02, n = 15). PMID:31213527 with endogenous Zdhhc23 protein largely expressed in perinuclear and other intracellular compartments consistent with Golgi and ER localization reported in other cell types. file:mouse/Zdhhc23/Zdhhc23-uniprot.txt PTHR22883:SF475; PALMITOYLTRANSFERASE ZDHHC23 |
| GO:0000139 Golgi membrane | ISS GO_REF:0000024 | ACCEPT | Summary: ISS transfer of Golgi membrane from human ZDHHC23 is sound; human and mouse are in the same ZDHHC23 subfamily. Reason: Mouse Zdhhc23 has six predicted transmembrane helices with the DHHC domain on the cytoplasmic side. The direct localization data come from tagged zDHHC23 in HEK293 cells (Golgi GM130 and TGN38 colocalization), and the gene sits in the ZDHHC23-specific PANTHER subfamily PTHR22883:SF475 with human ZDHHC23, so transfer is within orthologs. In mouse itself, endogenous Zdhhc23 in aortic smooth muscle cells is perinuclear, which is compatible with but does not by itself resolve a Golgi location. Golgi membrane is the appropriate granularity for a polytopic enzyme. Supporting Evidence: PMID:22399288 zDHHC23 predominantly co-localized with markers of the Golgi network (GM130, Pearson's R coefficient of 0.71 Β± 0.01, n = 15) and TGN (TGN38, Pearson's R coefficient of 0.38 Β± 0.02, n = 15). PMID:31213527 with endogenous Zdhhc23 protein largely expressed in perinuclear and other intracellular compartments consistent with Golgi and ER localization reported in other cell types. file:mouse/Zdhhc23/Zdhhc23-uniprot.txt PTHR22883:SF475; PALMITOYLTRANSFERASE ZDHHC23 |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: ER as a site of activity is a family-level PAINT inference from ER-resident paralogs; ZDHHC23-clade data point to Golgi/TGN. Reason: This IBA derives from the deep DHHC node PTN000525256 whose ER donors are other DHHC subfamilies (e.g. yeast ER-resident DHHCs and ZDHHC6-type proteins), not SF475. The ortholog data place ZDHHC23 at Golgi/TGN, and the authors place BK channel palmitoylation at the TGN. The mouse VSMC staining is perinuclear and the authors describe it only as consistent with previously reported Golgi and ER localization, which does not show activity in the ER. Not REMOVE, because ER residence has not been tested and excluded; the human ortholog row is treated the same way. Propagation Review Root cause: PROPAGATION BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: PANTHER:PTN000525256 SUPPORTS SOURCE BUT NOT TARGET Deep DHHC-family node with both ER and Golgi IBDs; the ER donors are ER-resident paralogs outside SF475. Supporting Evidence: PMID:22399288 zDHHC23 being predominantly localized at the Golgi apparatus and TGN, in agreement with previous studies (3, 4, 21), whereas the thioesterases were predominantly cytosolic (12, 20), supports a role for dynamic regulation of BK channel palmitoylation at the level of the TGN. PMID:31213527 with endogenous Zdhhc23 protein largely expressed in perinuclear and other intracellular compartments consistent with Golgi and ER localization reported in other cell types. |
| GO:0005794 Golgi apparatus | IBA GO_REF:0000033 | MODIFY | Summary: Golgi apparatus is correct but less specific than Golgi membrane, which the gene already carries. Reason: Zdhhc23 is a polytopic integral membrane enzyme acting on the cytoplasmic face of Golgi/TGN membranes (orthologous HEK293 localization data; perinuclear endogenous staining in mouse VSMCs). Refine to GO:0000139 Golgi membrane, already present on this gene (IEA SubCell and ISS rows). The IBA (deep DHHC node PTN000525256) and the SubCell IEA rows are refined the same way. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN000525256 SUPPORTS TRANSFER Golgi localization is correctly inherited for the ZDHHC23 clade; only granularity (Golgi apparatus vs Golgi membrane) is refined. Proposed replacements: Golgi membrane Supporting Evidence: PMID:22399288 zDHHC23 predominantly co-localized with markers of the Golgi network (GM130, Pearson's R coefficient of 0.71 Β± 0.01, n = 15) and TGN (TGN38, Pearson's R coefficient of 0.38 Β± 0.02, n = 15). PMID:31213527 with endogenous Zdhhc23 protein largely expressed in perinuclear and other intracellular compartments consistent with Golgi and ER localization reported in other cell types. |
| GO:0005794 Golgi apparatus | IEA GO_REF:0000044 | MODIFY | Summary: Golgi apparatus is correct but less specific than Golgi membrane, which the gene already carries. Reason: Zdhhc23 is a polytopic integral membrane enzyme acting on the cytoplasmic face of Golgi/TGN membranes (orthologous HEK293 localization data; perinuclear endogenous staining in mouse VSMCs). Refine to GO:0000139 Golgi membrane, already present on this gene (IEA SubCell and ISS rows). The IBA (deep DHHC node PTN000525256) and the SubCell IEA rows are refined the same way. Proposed replacements: Golgi membrane Supporting Evidence: PMID:22399288 zDHHC23 predominantly co-localized with markers of the Golgi network (GM130, Pearson's R coefficient of 0.71 Β± 0.01, n = 15) and TGN (TGN38, Pearson's R coefficient of 0.38 Β± 0.02, n = 15). PMID:31213527 with endogenous Zdhhc23 protein largely expressed in perinuclear and other intracellular compartments consistent with Golgi and ER localization reported in other cell types. |
| GO:0006612 protein targeting to membrane | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Palmitoylation-dependent membrane targeting of substrates is a family-level role; not the central description of Zdhhc23. Reason: The IBA comes from the deep DHHC node PTN000525256 (donors yeast Erf2 and a rice DHHC protein). Zdhhc23 adds the lipid that acts as the membrane-association/trafficking signal, so it does part of the work. However, in native mouse smooth muscle Zdhhc23 deletion did not alter BK alpha-subunit surface expression, so for this species the trafficking consequence is context dependent and is kept as non-core. Supporting Evidence: PMID:22399288 Overexpression of zDHHC23 resulted in a significant increase (by 144 Β± 5.3% of S0βS1-YFP alone) in cell surface expression of the S0βS1-YFP construct. PMID:31213527 Genetic deletion of Zdhhc23 or pharmacological inhibition of S-acylation reduced BK channel currents without affecting cell surface expression of BK channel Ξ±-subunits. |
| GO:0016409 palmitoyltransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: Palmitoyltransferase activity is correct but less specific than protein-cysteine S-palmitoyltransferase activity, which the gene already carries. Reason: The InterPro DHHC signature (IPR001594) and an intact DHHC motif with the C279 acyl-enzyme cysteine indicate S-acylation of protein cysteines; mouse knockout and knockdown data show dependence of BK channel and GFAP cysteine palmitoylation on Zdhhc23. Replace with GO:0019706. Proposed replacements: protein-cysteine S-palmitoyltransferase activity Supporting Evidence: file:mouse/Zdhhc23/Zdhhc23-uniprot.txt S-palmitoyl cysteine intermediate PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). |
| GO:0018345 protein palmitoylation | IMP PMID:22399288 Distinct acyl protein transferases and thioesterases control... | ACCEPT | Summary: Zdhhc23 is required for S-acylation of the BK channel S0-S1 loop; it catalyses this step. Reason: The cited study identified zDHHC23 (with zDHHC22) as the acyltransferase for the BK channel S0-S1 loop in an siRNA screen in HEK293 cells, with overexpression increasing surface delivery of the palmitoylation reporter. The curator recorded this against the mouse gene; I defer to that. The claim is independently established in mouse itself by Zdhhc23 knockout (PMID:31213527), which reduced endogenous BK alpha-subunit S-acylation in aortic smooth muscle, and by knockdown in a mouse astrocyte line reducing GFAP palmitoylation (PMID:38050183). Because the enzyme performs the acylation, the process term is appropriate. Supporting Evidence: PMID:22399288 palmitoylation of the intracellular S0-S1 loop of BK channels is controlled by two of the 23 mammalian palmitoyl-transferases, zDHHC22 and zDHHC23. PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). PMID:38050183 Further studies showed that GFAP significantly interacts with the palmitoyltransferase ZDHHC23 in astrocytes and that ZDHHC23 expression knockdown significantly downregulated GFAP palmitoyl modification levels. |
| GO:0018345 protein palmitoylation | ISO GO_REF:0000119 | ACCEPT | Summary: ISO transfer of protein palmitoylation from human ZDHHC23 is sound and is independently supported by mouse knockout data. Reason: Human ZDHHC23 and mouse Zdhhc23 are 1:1 orthologs in PANTHER subfamily PTHR22883:SF475. Mouse genetic deletion reduces endogenous BK alpha-subunit S-acylation, so this is experimentally established in mouse as well as transferred. Supporting Evidence: PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). file:mouse/Zdhhc23/Zdhhc23-uniprot.txt PTHR22883:SF475; PALMITOYLTRANSFERASE ZDHHC23 |
| GO:0019706 protein-cysteine S-palmitoyltransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Protein-cysteine S-palmitoyltransferase activity is inherited from the DHHC ancestor; Zdhhc23 retains the catalytic DHHC motif. Reason: PAINT placed this function at PTN000525256, covering the DHHC family. Zdhhc23 is inside that clade, retains DHHC (residues 276-279; C279 acyl-enzyme cysteine) and has its own species-level loss-of-function support. Mouse Zdhhc23 retains the catalytic DHHC motif (DHHC at residues 276-279, with C279 the S-palmitoyl cysteine intermediate). Its own experimental support is in mouse: Zdhhc23-/- aortic smooth muscle cells show a ~60% reduction in endogenous BK channel alpha-subunit S-acylation, and siRNA knockdown in a mouse astrocyte line reduces GFAP palmitoylation. These are loss-of-function data showing dependence of substrate acylation on the enzyme rather than in vitro catalysis with purified protein; the catalytic assignment rests on the conserved DHHC mechanism of the family together with these substrate data and the orthologous human data. Supporting Evidence: file:mouse/Zdhhc23/Zdhhc23-uniprot.txt S-palmitoyl cysteine intermediate PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). PMID:38050183 Further studies showed that GFAP significantly interacts with the palmitoyltransferase ZDHHC23 in astrocytes and that ZDHHC23 expression knockdown significantly downregulated GFAP palmitoyl modification levels. |
| GO:0019706 protein-cysteine S-palmitoyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: The Rhea/EC mapping (RHEA:36683, EC 2.3.1.225) to protein-cysteine S-palmitoyltransferase activity is correct. Reason: UniProt assigns the protein-cysteine palmitoylation reaction by similarity to human ZDHHC23 (same subfamily SF475). Mouse Zdhhc23 retains the catalytic DHHC motif (DHHC at residues 276-279, with C279 the S-palmitoyl cysteine intermediate). Its own experimental support is in mouse: Zdhhc23-/- aortic smooth muscle cells show a ~60% reduction in endogenous BK channel alpha-subunit S-acylation, and siRNA knockdown in a mouse astrocyte line reduces GFAP palmitoylation. These are loss-of-function data showing dependence of substrate acylation on the enzyme rather than in vitro catalysis with purified protein; the catalytic assignment rests on the conserved DHHC mechanism of the family together with these substrate data and the orthologous human data. Supporting Evidence: file:mouse/Zdhhc23/Zdhhc23-uniprot.txt S-palmitoyl cysteine intermediate PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). PMID:38050183 Further studies showed that GFAP significantly interacts with the palmitoyltransferase ZDHHC23 in astrocytes and that ZDHHC23 expression knockdown significantly downregulated GFAP palmitoyl modification levels. |
| GO:0019706 protein-cysteine S-palmitoyltransferase activity | ISO GO_REF:0000119 | ACCEPT | Summary: ISO transfer of protein-cysteine S-palmitoyltransferase activity from human ZDHHC23 is sound. Reason: Human and mouse ZDHHC23 are 1:1 orthologs in PANTHER subfamily PTHR22883:SF475. Mouse Zdhhc23 retains the catalytic DHHC motif (DHHC at residues 276-279, with C279 the S-palmitoyl cysteine intermediate). Its own experimental support is in mouse: Zdhhc23-/- aortic smooth muscle cells show a ~60% reduction in endogenous BK channel alpha-subunit S-acylation, and siRNA knockdown in a mouse astrocyte line reduces GFAP palmitoylation. These are loss-of-function data showing dependence of substrate acylation on the enzyme rather than in vitro catalysis with purified protein; the catalytic assignment rests on the conserved DHHC mechanism of the family together with these substrate data and the orthologous human data. Supporting Evidence: file:mouse/Zdhhc23/Zdhhc23-uniprot.txt S-palmitoyl cysteine intermediate PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). PMID:38050183 Further studies showed that GFAP significantly interacts with the palmitoyltransferase ZDHHC23 in astrocytes and that ZDHHC23 expression knockdown significantly downregulated GFAP palmitoyl modification levels. |
| GO:0019706 protein-cysteine S-palmitoyltransferase activity | ISS GO_REF:0000024 | ACCEPT | Summary: ISS transfer of protein-cysteine S-palmitoyltransferase activity from human ZDHHC23 is sound. Reason: Human and mouse ZDHHC23 are 1:1 orthologs in PANTHER subfamily PTHR22883:SF475. Mouse Zdhhc23 retains the catalytic DHHC motif (DHHC at residues 276-279, with C279 the S-palmitoyl cysteine intermediate). Its own experimental support is in mouse: Zdhhc23-/- aortic smooth muscle cells show a ~60% reduction in endogenous BK channel alpha-subunit S-acylation, and siRNA knockdown in a mouse astrocyte line reduces GFAP palmitoylation. These are loss-of-function data showing dependence of substrate acylation on the enzyme rather than in vitro catalysis with purified protein; the catalytic assignment rests on the conserved DHHC mechanism of the family together with these substrate data and the orthologous human data. Supporting Evidence: file:mouse/Zdhhc23/Zdhhc23-uniprot.txt S-palmitoyl cysteine intermediate PMID:31213527 Acyl-RAC performed on VSMCs from Zdhhc23β/β mice displayed a significant (βΌ60%) reduction in BK channel Ξ±-subunit S-acylation (Fig. 5A). PMID:38050183 Further studies showed that GFAP significantly interacts with the palmitoyltransferase ZDHHC23 in astrocytes and that ZDHHC23 expression knockdown significantly downregulated GFAP palmitoyl modification levels. |
| GO:0072659 protein localization to plasma membrane | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Zdhhc23-dependent palmitoylation can promote BK channel alpha-subunit delivery to the plasma membrane, but in native mouse tissue this effect was not seen. Reason: Zdhhc23 contributes the lipid modification that drives BK channel exit from the TGN in HEK293 cells lacking beta1 subunits (overexpression raised and knockdown lowered surface expression of the S0-S1 reporter and full-length channel). In mouse aortic smooth muscle, which expresses beta1, Zdhhc23 deletion reduced BK current but did not change alpha-subunit surface expression; the authors conclude that S-acylation controls surface expression only in the absence of beta1. The term is therefore true in some cellular contexts but is not a constant feature of the mouse enzyme, and is kept as non-core. The IBA comes from the ZDHHC23-specific node PTN008583751 (donors human ZDHHC23 and mouse Zdhhc23), so the propagation itself is within the ortholog clade. Supporting Evidence: PMID:22399288 Overexpression of zDHHC23 resulted in a significant increase (by 144 Β± 5.3% of S0βS1-YFP alone) in cell surface expression of the S0βS1-YFP construct. PMID:31213527 Genetic deletion of Zdhhc23 or pharmacological inhibition of S-acylation reduced BK channel currents without affecting cell surface expression of BK channel Ξ±-subunits. PMID:31213527 In the absence of the Ξ²1-subunit, S-acylation promotes cell surface expression, whereas in the presence of the Ξ²1-subunit, S-acylation controls functional coupling. |
| GO:0072659 protein localization to plasma membrane | IMP PMID:22399288 Distinct acyl protein transferases and thioesterases control... | KEEP AS NON CORE | Summary: Zdhhc23-dependent palmitoylation can promote BK channel alpha-subunit delivery to the plasma membrane, but in native mouse tissue this effect was not seen. Reason: Zdhhc23 contributes the lipid modification that drives BK channel exit from the TGN in HEK293 cells lacking beta1 subunits (overexpression raised and knockdown lowered surface expression of the S0-S1 reporter and full-length channel). In mouse aortic smooth muscle, which expresses beta1, Zdhhc23 deletion reduced BK current but did not change alpha-subunit surface expression; the authors conclude that S-acylation controls surface expression only in the absence of beta1. The term is therefore true in some cellular contexts but is not a constant feature of the mouse enzyme, and is kept as non-core. The IBA comes from the ZDHHC23-specific node PTN008583751 (donors human ZDHHC23 and mouse Zdhhc23), so the propagation itself is within the ortholog clade. Supporting Evidence: PMID:22399288 Overexpression of zDHHC23 resulted in a significant increase (by 144 Β± 5.3% of S0βS1-YFP alone) in cell surface expression of the S0βS1-YFP construct. PMID:31213527 Genetic deletion of Zdhhc23 or pharmacological inhibition of S-acylation reduced BK channel currents without affecting cell surface expression of BK channel Ξ±-subunits. PMID:31213527 In the absence of the Ξ²1-subunit, S-acylation promotes cell surface expression, whereas in the presence of the Ξ²1-subunit, S-acylation controls functional coupling. |
| GO:0072659 protein localization to plasma membrane | ISO GO_REF:0000119 | KEEP AS NON CORE | Summary: Zdhhc23-dependent palmitoylation can promote BK channel alpha-subunit delivery to the plasma membrane, but in native mouse tissue this effect was not seen. Reason: Zdhhc23 contributes the lipid modification that drives BK channel exit from the TGN in HEK293 cells lacking beta1 subunits (overexpression raised and knockdown lowered surface expression of the S0-S1 reporter and full-length channel). In mouse aortic smooth muscle, which expresses beta1, Zdhhc23 deletion reduced BK current but did not change alpha-subunit surface expression; the authors conclude that S-acylation controls surface expression only in the absence of beta1. The term is therefore true in some cellular contexts but is not a constant feature of the mouse enzyme, and is kept as non-core. The IBA comes from the ZDHHC23-specific node PTN008583751 (donors human ZDHHC23 and mouse Zdhhc23), so the propagation itself is within the ortholog clade. Supporting Evidence: PMID:22399288 Overexpression of zDHHC23 resulted in a significant increase (by 144 Β± 5.3% of S0βS1-YFP alone) in cell surface expression of the S0βS1-YFP construct. PMID:31213527 Genetic deletion of Zdhhc23 or pharmacological inhibition of S-acylation reduced BK channel currents without affecting cell surface expression of BK channel Ξ±-subunits. PMID:31213527 In the absence of the Ξ²1-subunit, S-acylation promotes cell surface expression, whereas in the presence of the Ξ²1-subunit, S-acylation controls functional coupling. |
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Download this section (compressed HTML)Q: Which endogenous proteins besides Kcnma1 are S-acylated by Zdhhc23 in brain and smooth muscle, and is GFAP a direct substrate?
Q: What enzyme accounts for the ~40% of BK alpha-subunit S-acylation that persists in Zdhhc23-/- smooth muscle; is it Zdhhc22?
Q: Does mouse Zdhhc23 reside or act in the ER, as propagated from the deep DHHC node, or only at Golgi/TGN membranes?
Experiment: Acyl-biotin exchange or click-chemistry palmitoyl-proteomics of Zdhhc23-/- versus wild-type brain and aortic smooth muscle, with rescue by wild-type versus C279S (DHHS) Zdhhc23, to define direct substrates.
Experiment: Endogenous Zdhhc23 colocalization with Golgi, TGN and ER markers in mouse VSMCs and neurons (knockout as antibody control) to settle its site of action.
Experiment: In vitro acylation of a Kcnma1 S0-S1 loop peptide by purified mouse Zdhhc23 with palmitoyl-CoA to demonstrate direct catalysis.
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