We have investigated the trafficking of the membrane-anchored form of human
ADAM 12 (ADAM 12-L) fused to a green fluorescence protein tag. Subcellular
localization of the protein in transiently transfected cells was determine
d by fluorescence microscopy and trypsin sensitivity. Full-length ADAM 12-L
was retained in a perinuclear compartment, which was shown to be the trans
-Glolgi network. In contrast, ADAM 12-L lacking the cytoplasmic domain reac
hed the cell surface. Based on analysis of deletions and mutations of the c
ytoplasmic tail of ADAM 12-L, the retention signal is comprised of both the
cytoplasmic and transmembrane domains, but not the Src homology 3 domain (
SH3) binding sites. These results raise the possibility that a trafficking
checkpoint in the trans-Gola network is one of the cellular mechanisms for
regulation of ADAM 12-L function, by allowing a rapid release of ADAM 12-L
to the cell surface under specific stimuli. (C) 2000 Academic Press.