This family of proteins includes muscle-related coiled-coil protein (MURC), protein kinase C delta-binding protein (PRKCDBP), polymerase I and transcript release factor (PTRF) and serum deprivation-response protein (SDPR). MURC activates the Rho/ROCK pathway. PRKCDBP appears to act as an immune potentiator. PTRF is involved in caveolae formation and function. SDPR is involved in the targetting of protein kinase Calpha to caveolae.