This entry also includes Transducer of Cdc42-dependent actin assembly protein (TOCA) family proteins which contains a central HR1 (also known as Rho effector motif class 1, REM-1) which is closely related to Cdc42-interacting protein 4 (CIP4), effectors of the Rho family small G protein Cdc2 [ PUBMED:27129201 ].

This entry also includes Transducer of Cdc42-dependent actin assembly protein (TOCA) family proteins which contains a central HR1 (also known as Rho effector motif class 1, REM-1) which is closely related to Cdc42-interacting protein 4 (CIP4), effectors of the Rho family small G protein Cdc2 [ PUBMED:27129201 ].

HR1 was first described as a three times repeated homology region of the N-terminal non-catalytic part of protein kinase PRK1(PKN) [ PUBMED:7851406 ]. The first two of these repeats were later shown to bind the small G protein rho [ PUBMED:8647255 PUBMED:9446575 ] known to activate PKN in its GTP-bound form. Similar rho-binding domains also occur in a number of other protein kinases and in the rho-binding proteins rhophilin and rhotekin. Recently, the structure of the N-terminal HR1 repeat complexed with RhoA has been determined by X-ray crystallography. This domain contains two long α helices forming a left-handed antiparallel coiled-coil fold termed the antiparallel coiled- coil (ACC) finger domain. The two long helices encompass the basic region and the leucine repeat region, which are identified as the Rho-binding region [ PUBMED:10619026 PUBMED:14514689 PUBMED:27129201 ].