Control of cystic fibrosis transmembrane conductance regulator expression by BAP31

Expression of the cystic fibrosis transmembrane conductance regulator (CFTR ) is stringently controlled by molecular chaperones participating in format ion of the quality control system. it has been shown that about 75% of all CFTR protein and close to 100% of the [Delta Phe(508)] CFTR variant are rap idly degraded before leaving the endoplasmic reticulum (ER). B cell antigen receptor-associated proteins (BAPs) are ubiquitously expressed integral me mbrane proteins that may control association with the cytoskeleton, vesicul ar transport, or retrograde transport from the cis Golgi to the ER. The pre sent study delivers evidence for cytosolic co-localization of both BAP31 an d CFTR and for the control of expression of recombinant CFTR in Chinese ham ster ovary (CHO) cells and Xenopus oocytes by BAP31. Antisense inhibition o f BAP31 in various cell types increased expression of both wild-type CFTR a nd [Delta Phe(508)]CFTR and enabled cAMP-activated CI- currents in [Delta P he(508)]CFTR-expressing CHO cells. Coexpression of CFTR together with BAP31 attenuated cAMP-activated CI- currents in Xenopus oocytes. These data ther efore suggest association of BAP31 with CFTR that may control maturation or trafficking of CFTR and thus expression in the plasma membrane.