The human receptor for urokinase plasminogen activator. NH2-terminal amino acid sequence and glycosylation variants.
The receptor for human urokinase-type plasminogen activator (u-PA) was purified from phorbol 12-myristate 13-acetate-stimulated U937 cells by temperature-induced phase separation of detergent extracts, followed by affinity chromatography with immobilized diisopropyl fluorophosphate-treated u-PA. The purified protein shows a single 55-60 kDa band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining. It is a heavily glycosylated protein, the deglycosylated polypeptide chain comprising only 35 kDa. The glycosylated protein contains N-acetyl-D-glucosamine and sialic acid, but no N-acetyl-D-galactosamine. Glycosylation is responsible for substantial heterogeneity in the receptor on phorbol ester-stimulated U937 cells, and also for molecular weight variations among various cell lines. The amino acid composition and the NH2-terminal amino acid sequence are reported. The protein has a high content of cysteine residues. The NH2-terminal sequence is not closely related to any known sequence. The identification of the purified and sequenced protein with the human u-PA receptor is based on the following findings: 1) the ability of the purified protein to bind u-PA and its amino-terminal fragment; 2) the identical electrophoretic mobilities observed for cross-linked conjugates, formed between either the purified protein or the u-PA receptor on intact U937 cells and the above ligands; 3) the identity of the apparent molecular weight of the purified protein to that predicted for the u-PA receptor in the same cross-linking studies; 4) the identical extent of glycosylation of the purified protein and of the u-PA receptor in crude membrane fractions, as detected after cross-linking; 5) the ability of antibodies raised against the purified protein to inhibit cellular binding of the amino-terminal fragment of u-PA.
Behrendt
N
N
Finsen Laboratory, Righospitalet, Copenhagen, Denmark.
Rønne
E
E
Ploug
M
M
Petri
T
T
Løber
D
D
Nielsen
L S
LS
Schleuning
W D
WD
Blasi
F
F
Appella
E
E
Danø
K
K
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002460:Cell Line; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000378:metabolism; D014644:Genetic Variation; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000302:isolation & purification; D055293:Receptors, Urokinase Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
D000596:Amino Acids; D004792:Enzyme Precursors; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate