Arp2 (Thr-237/Thr-238), Phosphospecific Antibody

Cellular morphology, adhesion, and motility occur through dynamic reorganization of actin-based superstructures. Actin-binding proteins are critical for regulating actin polymerization and superstructure formation. The Arp2/3 complex is an actin polymerization-inducing complex that includes Arp2, Arp3, p41-Arc, p34-Arc, p21-Arc, p20-Arc, and p16-Arc. Several nucleation promoting factors, such as WASP and coronin, regulate the activity of the Arp2/3 complex. In addition, the Arp2/3 complex may be regulated by phosphorylation of specific subunits in the complex. Arp2 has two phosphosites, Thr-237 and Thr-238, that are evolutionarily conserved, and are phosphorylated along with Tyr-202 in response to growth factor stimulation. These phosphorylation events may regulate binding to the pointed end of actin filaments, and alanine substitutions of these Arp2 phosphosites inhibit membrane protrusions. Thus, phosphorylation may be another mode of Arp2/3 complex regulation in addition to the activity of nucleation-promoting factors.

Phospho-Arp2 (Thr-237/Thr-238) synthetic peptide (coupled to KLH) corresponding to amino acid residues surrounding threonine 237 and threonine 238 in human Arp2.

The antibody detects 44 and 32 kDa* proteins corresponding to the molecular mass of Arp2 on SDS-PAGE immunoblots of human A431 and Jurkat cells treated with Calyculin A. This reactivity is not observed after lambda phosphatase treatment. This peptide sequence is highly conserved in rat, mouse, chicken, and fish Arp2 proteins.