Cell Cycle Associated Protein 1 (CAPRIN1)

The apical and basolateral borders of epithelial cells are distinguished by their different protein and lipid components. The sorting of newly synthesized membrane constituents to the appropriate region of the cell is accomplished either in the trans-Golgi network or by transcytosis, the selected transport of proteins to the appropriate surface. Transcytosis also is involved in the internalization of proteins and ligands at one surface and their transport to another. CAPRIN1 contains 3 distinct domains. The amino-terminal 275 residues contain several potential alpha helices, the middle region contains proline and glutamine-rich repeats, and residues 469 to 601 contain a potential GPI anchor site. Northern blot analysis showed 3.4- and 2.7-kb transcripts in all tissues examined; 5.3- and 2.0-kb mRNAs were also observed in testis.