Molecular cloning and characterization of EndoGlyx-1, an EMILIN-like multisubunit glycoprotein of vascular endothelium.
EndoGlyx-1, the antigen identified with the monoclonal antibody H572, is a pan-endothelial human cell surface glycoprotein complex composed of four different disulfide-bonded protein species with an apparent molecular mass of approximately 500 kDa. Here, we report the purification and peptide analysis of two EndoGlyx-1 subunits, p125 and p140, and the identification of a common, full-length cDNA with an open reading frame of 2847 base pairs. The EndoGlyx-1 cDNA encodes a protein of 949 amino acids with a predicted molecular mass of 105 kDa, found as an entry for an unnamed protein with unknown function in public data bases. A short sequence tag matching the cDNA of this gene was independently discovered by serial analysis of gene expression profiling as a pan-endothelial marker, PEM87. Bioinformatic evaluation classifies EndoGlyx-1 as an EMILIN-like protein composed of a signal sequence, an N-terminal EMI domain, and a C-terminal C1q-like domain, separated from each other by a central coiled-coil-rich region. Biochemical and carbohydrate analysis revealed that p125, p140, and the two additional EndoGlyx-1 subunits, p110 and p200, are exposed on the cell surface. The three smaller subunits show a similar pattern of N-linked and O-linked carbohydrates, as shown by enzyme digestion. Because the two globular domains of EndoGlyx-1 p125/p140 show structural features shared by EMILIN-1 and Multimerin, two oligomerizing glycoproteins implicated in cell-matrix adhesion and hemostasis, it will be of interest to explore similar functions for EndoGlyx-1 in human vascular endothelium.
Christian
S
S
Department of Oncology Research, Boehringer Ingelheim Pharma KG, 88397 Biberach an der Riss, Germany.
Ahorn
H
H
Novatchkova
M
M
Garin-Chesa
P
P
Park
J E
JE
Weber
G
G
Eisenhaber
F
F
Rettig
W J
WJ
Lenter
M C
MC
D000595:Amino Acid Sequence; D000954:Antigens, Surface; D001483:Base Sequence; D001798:Blood Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D000954:Antigens, Surface; D001798:Blood Proteins; D018076:DNA, Complementary; C089826:EMILIN3 protein, human; D008562:Membrane Glycoproteins; C030340:elastin microfibril interface located protein; C069282:multimerin