Table 1

Cleavage sites in IGFBP-3 produced by MMP-7

Cleavage sites in insulin-like growth factor binding protein 3 (IGFBP-3) produced by matrix metalloproteinase-7 (MMP-7) were determined by N-terminal sequence analysis as described under “Materials and Methods.” The NH2-terminal sequence of each fragment is shown with its apparent and calculated molecular weight. Each fragment was analyzed for the presence of the COOH terminal of IGFBP-3 by Western blot analysis with the anti-carboxy terminal peptides of IGFBP-3 monoclonal antibody (0.4 μg/ml). Because the N-glycosylation sites of IGFBP-3 are located at N89, N109, and N172, each fragment contained one glycosylated arginine residue.

Molecular weight (apparent, kDa)NH2-terminal sequenceN-G siteaMolecular weight (calculated, kDa)COOH-terminalb
Fragment Ac26G1ASSGGL125.3
Fragment Bc17I145IIIKKG117.7+
Fragment Cc15.5G1ASSGGL
(Fragment C1)116.3
15.5L96RXXLLP1 or 2Unknown
(Fragment C2)
  • a N-G site = N-linked glycosylation site.

  • b COOH-terminal = presence (+) or absence (−) of COOH terminal of IGFBP-3.

  • c The letters correspond to the cleavage products represented in Fig. 2 <$REFLINK> .