ZDHHC2

ZDHHC2 is a DHHC-motif protein S-acyltransferase (palmitoyltransferase) that controls the membrane targeting, stability, and signaling output of a broad set of substrates by attaching palmitate to their cysteines (PMID:18508921, PMID:18296695). Catalysis depends on an intact DHHC active site, since DH→AA or C→S mutations abolish substrate palmitoylation (PMID:18508921). The enzyme dynamically cycles between the plasma membrane and Rab11-positive recycling endosomes, with its cytoplasmic C-terminus — including a non-canonical dileucine [SxxxLL] motif and a downstream NP motif — directing endocytic retrieval and membrane localization; deletion of the C-terminus relocates the enzyme to the ER (PMID:21471008, PMID:28768144). Through this activity ZDHHC2 governs substrate trafficking and turnover: it palmitoylates CKAP4/p63 to drive its ER-to-plasma-membrane and nuclear localization and APF antiproliferative signaling (PMID:19144824, PMID:18296695), palmitoylates the tetraspanins CD9 and CD151 to promote their association and protect them from lysosomal degradation (PMID:18508921), and acylates R7BP and the kinase Lck to maintain their membrane association (PMID:21343290, PMID:22034844). In neurons, ZDHHC2 resident on recycling endosomes palmitoylates AKAP79/150 to enable recycling-endosome exocytosis, dendritic spine enlargement, and AMPAR potentiation during LTP, and is upregulated by fear conditioning to selectively augment AKAP150 palmitoylation and support fear memory (PMID:25589740, PMID:37664599). ZDHHC2 acts in immunity and infection by promoting IRF7 phosphorylation and IFN-α production in plasmacytoid dendritic cells (PMID:33488612), supporting germinal center B cell differentiation (PMID:32587588), and stabilizing B-RAF/C-RAF against autophagic degradation to drive ERK signaling that affects intracellular M. tuberculosis survival in macrophages (PMID:39854453). In cancer it palmitoylates AGK to activate PI3K-AKT-mTOR signaling and reduce sunitinib sensitivity in renal carcinoma (PMID:37078777), and palmitoylates the deubiquitinase USP19 to destabilize ACSL4 and suppress ferroptosis in prostate cancer (PMID:41126755). ZDHHC2 also acylates influenza A hemagglutinin and M2, and palmitoylates Gpm6a to support lipid raft formation and mammary stem cell activity (PMID:31872235, PMID:39321020).

1. 2008 Medium

   Establishing that ZDHHC2 is a bona fide palmitoyl acyltransferase required identifying a direct substrate; CKAP4/p63 was captured as a major substrate, defining a PAT-substrate relationship in a living vertebrate system.

   Evidence PICA palmitoyl-cysteine proteomics in living cells

   PMID:18296695

   Open questions at the time

   • Did not establish catalytic dependence via active-site mutagenesis
   • Single proteomics method, single lab
2. 2008 High

   To prove catalysis rather than mere association, active-site mutagenesis showed ZDHHC2 directly palmitoylates the tetraspanins CD9 and CD151, with DHHC-motif mutants inactive, linking acylation to substrate stability and cell-cell contact.

   Evidence Radioactive palmitate labeling, DHHC active-site mutagenesis, reciprocal Co-IP, siRNA knockdown

   PMID:18508921

   Open questions at the time

   • Mechanism by which palmitoylation protects tetraspanins from lysosomal degradation not resolved
   • No structural basis for substrate selection
3. 2009 Medium

   Loss-of-function defined the cellular consequence of CKAP4 palmitoylation: it controls ER-to-plasma-membrane and nuclear trafficking and is required for APF antiproliferative signaling.

   Evidence siRNA knockdown, immunocytochemistry, palmitoylation and proliferation assays

   PMID:19144824

   Open questions at the time

   • Mechanism coupling palmitoylation to nuclear import unclear
   • Single cell-context for the signaling phenotype
4. 2011 High

   Where ZDHHC2 acts was answered by live imaging showing dynamic cycling between plasma membrane and Rab11 recycling endosomes, with the C-terminus dictating localization distinct from the paralog DHHC15.

   Evidence Live-cell microscopy, FRAP, surface HA labeling, antibody-uptake, deletion/chimeric mutants

   PMID:21471008

   Open questions at the time

   • Trafficking machinery recognizing the C-terminus not identified at this stage
   • Note: one study reports primarily ER/Golgi localization (#5), indicating context dependence
5. 2011 Medium

   Two additional neuronal substrates extended the substrate range: ZDHHC2 mediates de novo and turnover palmitoylation of R7BP controlling its membrane-versus-nuclear distribution, and S-acylates Lck to maintain T cell kinase membrane association.

   Evidence siRNA knockdown/overexpression, palmitoylation turnover assays, subcellular fractionation

   PMID:21343290 PMID:22034844

   Open questions at the time

   • Discrepant localization (ER/Golgi vs recycling endosome) across studies unresolved
   • No direct demonstration of catalytic dependence for Lck
6. 2017 Medium

   The trafficking determinants were refined to a non-canonical dileucine [SxxxLL] motif and a downstream NP motif that drive endocytic retrieval, with phosphorylation potentially tuning their efficacy.

   Evidence Site-directed and phospho-mimetic mutagenesis, live-cell imaging in PC12 cells and neurons

   PMID:28768144

   Open questions at the time

   • Endogenous kinase regulating the sorting signals not identified
   • Adaptor recognizing the motifs not defined
7. 2015 High

   A causal role in synaptic plasticity was established by genetic epistasis: recycling-endosome-resident ZDHHC2 palmitoylates AKAP79/150 to enable spine enlargement and AMPAR potentiation during LTP, and a lipidation-independent AKAP mutant rescues the knockdown.

   Evidence RNAi, Co-IP, LTP electrophysiology, live imaging, epistatic rescue in hippocampal neurons

   PMID:25589740

   Open questions at the time

   • How activity regulates ZDHHC2-AKAP engagement during LTP unclear
   • Other neuronal substrates contributing to plasticity not excluded
8. 2020 High

   Substrate scope and physiological roles broadened to immunity and viral infection: ZDHHC2 supports germinal center B cell differentiation and is among the strongest acyltransferases for influenza A HA and M2.

   Evidence In vivo shRNA screen and B cell assays; siRNA library, Acyl-RAC, 3H-palmitate, CRISPR KO, co-localization for influenza substrates

   PMID:31872235 PMID:32587588

   Open questions at the time

   • Substrate(s) mediating the B cell differentiation phenotype not identified
   • Specificity for influenza A versus B/C HA mechanistically unexplained
9. 2021 Medium

   A signaling-level role in innate immunity was defined: ZDHHC2 is required for IRF7 phosphorylation and IFN-α production in plasmacytoid dendritic cells, with knockout mice showing reduced pDC accumulation and IFN-α in psoriatic skin.

   Evidence CRISPR/Cas9 KO mouse and human CAL-1 pDC KO, IRF7 phosphorylation assay, cytokine ELISA, flow cytometry

   PMID:33488612

   Open questions at the time

   • Direct palmitoylation substrate linking ZDHHC2 to IRF7 phosphorylation not identified
   • Whether the effect requires catalytic activity not tested
10. 2023 Medium

    ZDHHC2 was implicated in cancer signaling and drug resistance by palmitoylating AGK to promote its plasma-membrane translocation and PI3K-AKT-mTOR activation, lowering sunitinib sensitivity, and by augmenting AKAP150 palmitoylation upon fear learning to support memory and LTP.

    Evidence Palmitoylation and membrane translocation assays, pathway activity, tumor models; viral shRNA, fear conditioning, LTP, palmitoylation assays

    PMID:37078777 PMID:37664599

    Open questions at the time

    • AGK palmitoylation site(s) not mapped
    • Whether ZDHHC2 catalytic activity is required for memory phenotype not isolated
11. 2024 Medium

    Site-resolved mechanism was extended to development: ZDHHC2 (with ZDHHC1) palmitoylates Gpm6a at Cys17/18/246 to drive lipid raft formation that stabilizes Procr and sustains mammary stem cells.

    Evidence Knockout mouse, palmitoylation site mapping by mutagenesis, lipid raft fractionation, protein stability assay

    PMID:39321020

    Open questions at the time

    • Relative contribution of ZDHHC1 versus ZDHHC2 not dissected
    • How raft formation stabilizes Procr mechanistically unclear
12. 2025 Medium

    ZDHHC2 was placed within proteostasis-coupled signaling cascades: it palmitoylates B-RAF/C-RAF to block their autophagic degradation and sustain ERK signaling controlling M. tuberculosis survival, and palmitoylates USP19 to destabilize ACSL4 and suppress ferroptosis in prostate cancer, where ZDHHC2 is transcriptionally driven by a FOXA1/CXXC5/TET2 complex.

    Evidence ZDHHC2 KO/KD in macrophages with autophagy and ERK assays; palmitoylation, Co-IP, ubiquitination assays, PDX, small-molecule inhibitor TTZ1

    PMID:39854453 PMID:41126755

    Open questions at the time

    • Palmitoylation sites on B-RAF/C-RAF and USP19 not fully mapped
    • How palmitoylation of USP19 alters its substrate engagement mechanistically incomplete

• A unifying structural and regulatory model is still missing: how ZDHHC2 selects its diverse substrates, how its localization (recycling-endosome versus ER/Golgi reports differ) dictates substrate access, and how upstream signals tune its activity across tissues remain unresolved.
• No structural model of substrate recognition
• Localization discrepancies across studies unreconciled
• Catalytic-dependence not tested for several physiological phenotypes