[9] βPIX contains a central DH/PH RhoGEF domain that functions as a guanine nucleotide exchange factor (GEF) for small GTPases of the Rho family, and specifically Rac and Cdc42.

In the case of βPIX, its SH3 domain binds to partner proteins with appropriate polyproline motifs, and particularly to group I p21-activated kinases (PAKs) (PAK1, PAK2 and PAK3).

In contrast, β2 carboxyl terminal variants lack this coiled-coil region and are predicted to be unable to trimerize.

Some splice variants of βPIX contain an amino-terminal Calponin Homology (CH) domain whose functions remain relatively poorly defined, but may interacts with parvin/affixin family proteins.

[13][9] βPIX variants with this extended amino terminal CH domain are most highly expressed early in development, but appear rare after birth.