AN INTEGRAL MEMBRANE COMPONENT OF COATOMER-COATED TRANSPORT VESICLES DEFINES A FAMILY OF PROTEINS INVOLVED IN BUDDING

We have isolated a major integral membrane protein from Golgi derived coatomer-coated vesicles, This 24-kDa protein, p24, defines a family o f integral membrane proteins with homologs present in yeast and humans , In addition to sequence similarity, all p24 family members contain a motif with the characteristic heptad repeats found in coiled coils, W hen the yeast p24 isoform, yp24A, is knocked out in a strain defective for vesicle fusion, a dramatic reduction in the accumulation of trans port vesicles is observed, Together, these results indicate a role for this protein family in the budding of coatamer-coated and other speci es of coated vesicles.