The human receptor for urokinase plasminogen activator. NH2-terminal amino acid sequence and glycosylation variants

N Behrendt, E Rønne, M Ploug, T. Petri, D. Løber, Lars S Nielsen, W.D. Schleuning, F. Blasi, E Appella, K Danø

Abstract

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.

Original languageEnglish
JournalThe Journal of Biological Chemistry
Volume265
Issue number11
Pages (from-to)6453-60
Number of pages8
ISSN0021-9258
Publication statusPublished - 15 Apr 1990
Externally publishedYes

Keywords

  • Amino Acid Sequence
  • Amino Acids
  • Cell Line
  • Chromatography, Affinity
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Precursors
  • Genetic Variation
  • Glycosylation
  • Humans
  • Molecular Sequence Data
  • Molecular Weight
  • Receptors, Cell Surface
  • Receptors, Urokinase Plasminogen Activator
  • Tetradecanoylphorbol Acetate
  • Urokinase-Type Plasminogen Activator
  • Journal Article
  • Research Support, Non-U.S. Gov't

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