TRAP proteins are part of a complex whose function is to bind calcium to the ER membrane and thereby regulate the retention of ER resident proteins. Heterotrimer of TRAP-alpha, TRAP-beta and TRAP-gamma. Shows a remarkable charge distribution with the N-terminus being highly negatively charged, and the cytoplasmic C-terminus positively charged. Phosphorylated in its cytoplasmic tail. Seems to bind calcium. Belongs to the TRAP-alpha family.