Gas-1

Gas1 (Growth Arrest Specific 1) is one of six structurally unrelated proteins that were identified by their increased expression in growth-arrested cells relative to actively proliferating cells. Following mitogenic stimulation, Gas1 expression is transcriptionally suppressed by c-Myc as cells transit from G0 to G1 phases of the cell cycle. Overexpression of Gas1 prevents S phase entry and DNA synthesis. Gas1-mediated blockade of the cell cycle is p53-dependent but does not require the transactivating domain of p53. The human Gas1 cDNA encodes a 345 amino acid (aa) precursor that includes a 39 aa signal sequence, a 279 aa mature protein, and a 27 aa C-terminal propeptide. Gas1 contains Ala-rich and Asp-rich regions as well as an RGD sequence. Mature human and mouse Gas1 share 85% aa sequence identity. Human Gas1 is a 40 kDa GPI-linked glycoprotein that is uniformly distributed on the cell surface. In contact-inhibited vascular endothelial cells, Gas1 is induced by VE-Cadherin and VEGF expression and mediates the anti-apoptotic effect of VEGF.