Fig. 1. Properties of PIX. (A) Different isoforms of PIX. Abbreviations: CH, calponin homology domain; SH3, Src homology 3; DH, Dbl homology domain; PH, pleckstrin homology domain; inverted triangle, deletion in PIX; I, insert sequence of 30 amino acids in ß1PIX and ß2PIX not present in PIX; II, insert sequence of 60 amino acids present in ß2PIX, ß1PIX-b and ß1PIX-c. The numbers represent the percentage similarity between the domains of PIX and ß1PIX. ß1PIX-b, ß1PIX-c and ß2PIX are all splice variants of ß1PIX. (B) Alignment of the C termini of PIX, ß1PIX and ß2PIX. The C termini of PIX and ß1PIX contain a coiled-coil structure, whereas that of ß2PIX is serine rich. The consensus sequences are boxed. The inverted arrowheads mark the start of the coiled-coil regions of PIX and ß1PIX, and also the serine-rich region of ß2PIX. The major PAK phosphorylation sites are marked with asterisks. The GIT1 binding region is from residues 460 to 555 of ß1PIX. (C) Western analysis of cell lysates of different tissues from rat and also several cell lines. The membranes were probed with anti-PIX-SH3 antibodies (top and middle), which recognized all isoforms of PIX, and with anti-ß2PIX-C-terminus antibodies (bottom), which only recognized the ß2 isoforms. Abbreviations for the rat tissue protein lysates: B, brain; K, kidney; Li, liver; Lu, lung; S, spleen; Te, testis; Th, thymus. Abbreviations for the cell line protein lysates (middle): C, COS-7; H, HeLa; N, NIH 3T3; K, kidney protein lysates; F, pXJ-Flag-ß1PIX transfected COS-7 cell lysate.