An endothelial cell receptor for plasminogen/tissue plasminogen activator. I. Identity with annexin II.
Sequencing of two internal peptides from the putative human endothelial cell tissue plasminogen activator (t-PA) receptor identified an analog of the calcium- and phospholipid-binding protein, annexin II (Ann-II). The polymerase chain reaction-derived, full-length cDNA revealed complete sequence identity with the heavy chain of Ann-II, and ligand-precipitated receptor protein immunoreacted specifically with a monoclonal antibody to Ann-II. Transfected 293 cells bound plasminogen (Kd = 114 nM; Bmax = 347,000) as well as t-PA (Kd = 48 nM; Bmax = 380,000). Antisense oligonucleotides directed against endothelial cell Ann-II mRNA inhibited binding of both t-PA and plasminogen by 49% and 38%, respectively. The K307T mutant of Ann-II expressed on 293 cells failed to bind plasminogen, while the K328I mutant bound this ligand in a manner equivalent to the wild-type. Binding of plasminogen to both the wild-type and the K328I mutant was blocked by pretreatment of 293 cells with carboxypeptidase B. These data suggest a novel mechanism whereby a plasmin-like serine protease may cleave Ann-II at Lys307-Arg308, exposing a new carboxyl-terminal lysine residue (Lys307) for binding and efficient activation of plasminogen.
Hajjar
K A
KA
Department of Pediatrics, Cornell University Medical College, New York, New York 10021.
Jacovina
A T
AT
Chacko
J
J
D000595:Amino Acid Sequence; D017306:Annexin A2 / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002478:Cells, Cultured; D018076:DNA, Complementary; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D017306:Annexin A2; D018076:DNA, Complementary; D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface; C067262:PLAT protein, human; D010959:Tissue Plasminogen Activator