CLONING AND EXPRESSION OF A PLANT HOMOLOG OF THE SMALL-SUBUNIT OF THEGOLGI-ASSOCIATED CLATHRIN ASSEMBLY PROTEIN AP19 FROM CAMPTOTHECA-ACUMINATA

Clathrin-coated vesicles (CCVs) are involved in selective protein tran sport in eukaryotes. AP-1 and AP-2 are protein complexes found in the CCVs of the Golgi apparatus and the plasma membrane respectively. AP19 is the smallest polypeptide chain components of AP-1. We have identif ied a cDNA clone (CAP19) encoding a putative homologue for the assembl y protein AP19 from the Chinese medicinal tree, Camptotheca acuminata. The deduced polypeptide contains 161 amino acids and has a predicted M(r) of 18 820. DNA blot analysis suggests that the AP19s of C. acumin ata are encoded by a small gene family. CAP19 was expressed ubiquitous ly throughout the plant suggesting that it may be involved in general Golgi-mediated secretion.