Identity of urinary trypsin inhibitor-binding protein to link protein

Hiroshi Kobayashi, Yasuyuki Hirashima, Guang Wei Sun, Michio Fujie, Takashi Nishida, Masaharu Takigawa, Toshihiko Terao

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Urinary trypsin inhibitor (UTI), a Kunitz-type protease inhibitor, directly binds to some types of cells via cell-associated UTI-binding proteins (UTI-BPs). Here we report that the 49-kDa protein (UTI-BP40) was purified from the cultured human chondrosarcoma cell line HCS-2/8 by UTI affinity chromatography. Purified UTI- BP40 was digested with trypsin, and the amino acid sequences of the peptide fragments were determined. The sequences of six tryptic fragments of UTI-BP40 were identical to subsequences present in human link protein (LP). Authentic bovine LP and UTI- BP40 displayed identical electrophoretic and chromatographic behavior. The UTI-binding properties of UTI-BP40 and LP were indistinguishable. Direct binding and competition studies strongly demonstrated that the NH2-terminal fragment is the UTI-binding part of the LP molecule, that the COOH-terminal UTI fragment (HI-8) failed to bind the NH2-terminal subdomain of the LP molecule, and that LP and UTI-BP40 exhibited significant hyaluronic acid binding. These results demonstrate that UTI-BP40 is identical to LP and that the NH2-terminal domain of UTI is involved in the interaction with the NH2-terminal fragment of LP, which is bound to hyaluronic acid in the extracellular matrix.

Original languageEnglish
Pages (from-to)21185-21191
Number of pages7
JournalJournal of Biological Chemistry
Issue number28
Publication statusPublished - Jul 14 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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