The glycosylation pattern of human vascular endothelial cadherin (VE-cadher
in), purified from cultured human umbilical cord vein endothelial cells, wa
s analyzed. VE-cadherin was metabolically radiolabeled with D-[6-H-3]glucos
amine, isolated by immunoprecipitation, purified by SDS-PAGE and in-gel dig
ested with endoproteinase Asp N, Oligosaccharides were sequentially release
d from resulting glycopeptides and analyzed by chromatographic profiling. T
he results revealed that VE-cadherin carries predominantly sialylated diant
ennary and hybrid-type glycans in addition to some triantennary and high ma
nnose-type species. Highly branched, tetra-antennary oligosaccharides were
found in trace amounts only. Immunohistochemical labeling of VE-cadherin an
d sialic acids displayed a codistribution along the intercellular junctions
in endothelial cells of human umbilical arteries, veins, and cultured endo
thelial monolayers, Ca2+-depletion, performed on cultured endothelial cells
, resulted in a reversible complete disappearance of VE-cadherin and of alm
ost all sialic acid staining from the junctions. Sialidase treatment of who
le cells caused a change of VE-cadherin immunofluorescence from a continuou
s and netlike superstructural organization to a scattered inconsistent one.
Hence, cell surface sialic acids might play a role in VE-cadherin organiza
tion.