NAA30

NAA30 is the catalytic subunit of the NatC N-terminal acetyltransferase complex, which co-translationally acetylates protein N-termini at the ribosome (PMID:12507466, PMID:12890471, PMID:17541948). Together with the auxiliary subunits NAA35 and NAA38, NAA30 acetylates substrates beginning with Met followed by a bulky hydrophobic or amphipathic residue, with proteome-wide N-terminomics defining a substrate repertoire spanning ML, MI, MF, MW, and additional MV/MM/MK/MY/MA/MS N-termini (PMID:27694331, PMID:36567016). Structurally, NAA38 broadens NAA30 substrate specificity and increases complex thermostability by ordering the NAA35 N-terminal segment and reorienting an NAA30 peptide-binding loop, while inositol hexaphosphate (IP6) binds and stabilizes the assembled complex (PMID:34019809, PMID:36638802). NAA30 activity is required for organellar integrity: its depletion collapses mitochondrial membrane potential and fragments mitochondria (PMID:27694331), and disperses the Golgi apparatus through mislocalization of the substrate ARFRP1 (PMID:28356483). NAA30 N-terminally acetylates ARPC1B, protecting it from polyubiquitination and proteasomal degradation, a function exploited in ovarian cancer where NAA30 is transcriptionally driven by NR2C2 (PMID:41615304). In glioblastoma-initiating cells, NAA30 supports viability, sphere formation, and hypoxia tolerance (PMID:26292663), and the NatC complex confers resistance to ER stress downstream of the ATF6 arm of the UPR, protecting against muscle wasting in cancer cachexia (PMID:41852114). The full-length cytoplasmic enzyme, but not a catalytically inactive nuclear splice variant, possesses NAT activity and promotes cell survival (PMID:29247799).

1. 2003 High

   Established the foundational identity of NatC by showing NAA30 is the catalytic subunit acting with two auxiliary subunits and defining its Met-X substrate signature, framing all subsequent mechanistic work.

   Evidence Biochemical characterization and substrate sequence analysis of yeast Mak3p/NatC across hundreds of yeast and mammalian proteins

   PMID:12507466 PMID:12890471

   Open questions at the time

   • Substrate scope defined by sequence inference, not exhaustive in vivo proteomics
   • Structural basis of catalysis and subunit cooperation unknown at this stage
2. 2008 Medium

   Answered where NatC acts by localizing the complex to ribosomes, establishing co-translational acetylation as its mode of action.

   Evidence Sucrose density gradient fractionation and TAP-affinity purification in yeast

   PMID:17541948

   Open questions at the time

   • Does not define which nascent chains are engaged co-translationally
   • Single lab; ribosome association in human cells not directly demonstrated here
3. 2016 High

   Defined the human NAA30 substrate set in vivo and linked its activity to a concrete organellar phenotype, showing acetylation is required for mitochondrial integrity.

   Evidence NAA30 knockdown with positional proteomics, membrane potential assay, and fluorescence microscopy in human cells

   PMID:27694331

   Open questions at the time

   • Which specific mitochondrial substrate(s) mediate the phenotype not pinpointed
   • Mechanism linking lost N-acetylation to membrane potential collapse unresolved
4. 2017 Medium

   Extended NAA30 function to Golgi maintenance by identifying ARFRP1 as a likely substrate whose localization depends on NatC activity.

   Evidence shRNA knockdown in HeLa and CAL-62 cells with immunofluorescence of Golgi markers and ARFRP1

   PMID:28356483

   Open questions at the time

   • Direct N-acetylation of ARFRP1 by NAA30 not demonstrated biochemically
   • ARFRP1 retains membrane association, so the molecular consequence of mislocalization is unclear
5. 2017 Medium

   Distinguished NAT-active full-length NAA30 from an inactive nuclear splice variant, tying catalytic competence to subcellular localization and a pro-survival anti-apoptotic role.

   Evidence In vitro acetyltransferase assay, localization microscopy, and viability/apoptosis assays comparing Naa30 isoforms

   PMID:29247799

   Open questions at the time

   • Physiological function of the nuclear variant unknown
   • Mechanism linking acetyltransferase activity to apoptosis inhibition not defined
6. 2021 Medium

   Demonstrated functional conservation by showing human NAA30 rescues yeast mak3Δ phenotypes, validating cross-species use of yeast as a model for human NatC.

   Evidence Genetic complementation of yeast mak3Δ strains with human NAA30 and stress growth assays

   PMID:33600573

   Open questions at the time

   • Rescue at growth level does not confirm identical substrate spectra across species
   • Single lab
7. 2021 High

   Resolved the architecture of the trimeric complex, establishing that all three subunits are needed for activity and that IP6 is an integral stabilizing cofactor.

   Evidence Cryo-EM of S. pombe NatC with a bisubstrate analog and IP6, plus biochemical assays and mutagenesis

   PMID:34019809

   Open questions at the time

   • Mechanism distinguishing NatC from NatE substrate preference only partially explained
   • Human complex structure not yet resolved at this point
8. 2022 High

   Expanded the experimentally validated NatC substrate repertoire and revealed redundancy with NatE/Naa50 for certain N-termini, refining substrate boundaries.

   Evidence N-terminal COFRADIC on naa30Δ yeast with human NAA30 complementation

   PMID:36567016

   Open questions at the time

   • Extent of NatC/NatE redundancy in human cells not quantified
   • Functional consequences of acetylating the newly identified substrates unknown
9. 2023 High

   Mechanistically explained how the auxiliary subunit NAA38 tunes NAA30, showing it broadens substrate specificity and stabilizes the complex by reorganizing the catalytic peptide-binding loop.

   Evidence Cryo-EM of human NatC ± NAA38 with biochemical and thermostability assays

   PMID:36638802

   Open questions at the time

   • Whether NAA38 occupancy is regulated in cells is unknown
   • In vivo substrate shifts attributable to NAA38 not mapped
10. 2026 Medium

    Connected NAA30 acetylation to substrate protein stability and a cancer pathway, showing N-acetylation of ARPC1B prevents its degradation under NR2C2 transcriptional control.

    Evidence IP-LC/MS, N-acetylation omics, ubiquitination and rescue assays, and promoter luciferase assays in ovarian cancer cells

    PMID:41615304

    Open questions at the time

    • Direct causal link between the specific acetyl mark and ubiquitin protection not isolated
    • Single lab; generality beyond ovarian cancer untested
11. 2026 Medium

    Placed the NatC complex in the ER-stress/UPR response, identifying it as a determinant of ER stress resistance and muscle preservation in cachexia.

    Evidence Genome-wide CRISPR screen in C2C12 myoblasts with ATF6 modulation and in vivo AAV knockdown in tumor-bearing mice

    PMID:41852114

    Open questions at the time

    • Primary mechanistic focus is on NAA35; NAA30-specific contribution inferred from complex membership
    • Which acetylated substrates mediate ER stress resistance not identified

• The molecular link between loss of N-terminal acetylation of specific substrates and the downstream organellar and disease phenotypes remains undefined.
• No substrate-resolved mechanism connecting acetylation loss to mitochondrial/Golgi collapse
• Regulation of NAA30 activity in human tissues largely uncharacterized