since na+/k+ adenosine triphosphatase and ggtpase , respectively , mark the basolateral and apical cellular surfaces in other epithelia , we hypothesize that these two enzymes mark distinct domains in the parotid plasmalemma , and that ggtpase , as the putative apical marker , may signify a compositional overlap between the two types of membranes which fuse during exocytosis .
C0007634
cellular
C0007603
plasmalemma