Transmembrane Emp24 Protein Transport Domain Containing Protein 2 (TMED2)

The rat-p24 sequence is identical to the hamster CHOp24, a recently characterized component of coatomer-coated transport vesicles, which defines a family of proteins proposed to be involved in vesicular transport processes. Sequence alignment and structural features identify the Tmp21 protein as a new member of this p24 family. The integral membrane components Tmp21 and p24A are localized in microsomal membranes, zymogen granule membranes, and the plasma membrane and are absent from the cytosol. Both p24A and Tmp21 show weak homology to the yeast protein Emp24p, which recently has been shown to be involved in secretory protein transport from the endoplasmic reticulum to the Golgi apparatus.