A 55,000-60,000 Mr receptor protein for urokinase-type plasminogen activator. Identification in human tumor cell lines and partial purification.
The iodinated Mr approximately equal to 15,000 amino-terminal fragment (ATF) of the urokinase-type plasminogen activator (u-PA) molecule bound specifically to the cell surface of all of seven cultured human tumor cell lines studied. Cross-linking of iodinated ATF to the cell surface using a bifunctional amino-reactive reagent followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed with the four cell lines studied the occurrence of a single band migrating with an Mr of 70,000-75,000, indicating complex formation with an Mr of 55,000-60,000 u-PA receptor protein (u-PA-R). In the human monocyte cell line U937 cultivated in the presence of phorbol ester, the amount of complex was strongly increased, and a fraction of the complex had a slower electrophoretic mobility. Comparison between autoradiograms of reduced and unreduced samples suggests that u-PA-R consists of one polypeptide chain. Two forms of u-PA-R, which differed with respect to affinity to concanavalin A, were identified. u-PA-R retained its ability to bind to ATF after cell lysis, and it was purified approximately 2,200-fold from biosynthetically labeled U937 cells by affinity chromatography with proenzyme u-PA coupled to Sepharose. The purified Mr 55,000-60,000 protein was specifically bound and cross-linked to u-PA, proenzyme u-PA, and ATF, but not to tissue-type plasminogen activator or other unrelated proteins.
Nielsen
L S
LS
Finsen Laboratory, Rigshospitalet, Copenhagen, Denmark.
Kellerman
G M
GM
Behrendt
N
N
Picone
R
R
Danø
K
K
Blasi
F
F
D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D010960:Plasminogen Activators / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D014407:Tumor Cells, Cultured / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator