Anti-p190-A RhoGAP

The Rho family of small GTPases, including Rho, Rac and Cdc42, are key regulators of diverse biological processes such as cytoskeletal organization, cell growth and differentiation, transcriptional regulation, and cell adhesion/motility (1,2). The activities of these proteins are controlled by GTP binding such that in the GTP-bound state they are active, and in the GDP-bound state they become inactive. Three classes of regulatory proteins control the activity of the GTPases by balancing the levels of GTP/GDP binding: the guanine nucleotide exchange factors (GEFs), which promote the active state by facilitating the exchange of GDP for GTP, the guanine nucleotide dissociation inhibitors (GDIs), which sequester the GDP-bound forms and may regulate their intracellular localization, and the GTPase activating proteins (GAPs), which increase GTP hydrolysis to promote the inactive state. The p190 RhoGAP family consists of two related proteins, p190-A and p190-B, which are both widely expressed and contain an amino-terminal GTPase domain and a carboxy-terminal RhoGAP catalytic domain. Mice lacking p190-B RhoGAP show excessive Rho activation and a reduction in activation of the transcription factor CREB (3). Phenotypes of these mice are similar to those of CREB knockouts, with reduced cell size, as well as defects in thymus and neural development (3). Cells deficient in p190-B also display defective adipogenesis, suggesting this pathway is critical for the "adipogenesismyogenesis switch." (4). There is increasing evidence that p190 undergoes tyrosine phosphorylation, which activates its GAP domain (4-6). Levels of tyrosine phosphorylation are enhanced by Src overexpression (5,6). IGF-1 treatment downregulates Rho through phosphorylation and activation of p190-B RhoGAP, thereby enhancing IGF signaling implicated in adipogenesis (4). p190-A has been characterized as a tumor suppressor based on its ability to reverse v-Ha-Ras-induced malignancy in cultured cells (7). Loss or rearrangement of the chromosomal region containing the gene for p190-A has been implicated in the development of some human tumors (8). p190-A can also bind the mitogen-inducible transcription factor TFII-I sequestering it in the cytoplasm and inhibiting its activity. Phosphorylation of p190-A at Tyr308 reduces its affinity for TFII-I, relieving the inhibition (9). p190-A can also inhibit growth factor-induced gliomas in mice (10) and affect cleavage furrow formation and cytokinesis in cultured cells (11). Applications: Suitable for use in Western Blot. Other applications not tested. Recommended Dilution: Western Blot: 1:1000 Optimal dilutions to be determined by the researcher. Storage and Stability: For long-term storage, aliquot and store at -20°C. Aliquots are stable for 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.