ARD1A (E1J2B) Rabbit mAb #13357

Protein acetylation is a common modification that occurs both at lysine residues within proteins (ε-amino acetylation) and multiple amino acid residues at the amino terminus of proteins (α-amino acetylation). The N-α-acetyltransferase ARD1 homolog A protein (ARD1A, also known as NAA10) and the highly homologous N-α-acetyltransferase ARD1 homolog B protein (ARD1B, also known as ARD2 or NAA11) are mutually exclusive catalytic subunits of the amino-terminal acetyltransferase complex (NatA) (1-3). This complex, which consists of either ARD1A or ARD1B and the N-α-acetyltransferase 15 (NAA15) auxiliary protein, localizes to ribosomes where it functions to acetylate Ser-, Ala-, Gly-, Thr-, Cys-, Pro-, and Val- amino termini after initiator methionine cleavage during protein translation (1-5). Like ε-amino acetylation, amino-terminal α-amino acetylation functions to regulate protein stability, activity, cellular localization, and protein-protein interactions (4,5). Defects in ARD1A have been shown to cause amino-terminal acetyltransferase deficiency (NATD), which results in severe delays and defects in postnatal growth (6).

In addition to functioning as amino-terminal acetyltransferases in the NatA complex, free ARD1A and ARD1B proteins regulate cell growth and differentiation through ε-amino acetylation of lysine residues in multiple target proteins, including the HIF-1α, β-catenin, and AP-1 transcription factors (7-9). ARD1A-mediated acetylation of HIF-1α at Lys532 under normoxic conditions enhances binding of VHL, leading to increased ubiquitination and degradation of HIF-1α and down-regulation of HIF-1α target genes involved in angiogenesis, apoptosis, cellular proliferation, and glucose metabolism (7). Decreased expression of ARD1A under hypoxic conditions contributes to the stabilization of HIF-1α and upregulation of target genes (7). ARD1A also promotes cell proliferation and tumorigenesis by acetylating and activating β-catenin and AP-1 transcription factors, leading to the stimulation of cyclin D1 expression (8,9). Interestingly, the acetyltransferase activity of ARD1A is regulated by autoacetylation at Lys136, which is required for the ability of ARD1A to promote proliferation and tumorigenesis (9). Research studies have shown that ARD1 proteins are over-expressed in multiple cancers, including breast, prostate, lung, and colorectal cancers (10-13).