Abstract
A lactose-binding lectin from rat lung (RL-29) and a related lectin from Madin-Darby canine kidney (MDCK) cells have been analyzed with the primary goal of identifying post-translational modifications. The sequences show that RL-29 and the dog lectin are homologues of a lectin designated here as L-29 and elsewhere as CBP-35, epsilon BP, Mac-2, or L-34. RL-29 has a 140-amino-acid COOH-terminal carbohydrate-binding domain, a 20-amino-acid NH2-terminal domain, and an intervening domain consisting of 11 repeating elements rich in Pro, Gly, and Tyr (R-domain). The dog homologue has 14 repeating elements in its R-domain explaining its larger size. The sensitivity of the R-domain to bacterial collagenase allowed us to isolate the NH2-terminal domain and show that the NH2 terminus was blocked by acetylation and, in the accompanying paper (Huflejt, M. E., Turck, C. W., Lindstedt, R., Barondes, S. H., and Leffler, H. (1993) J. Biol. Chem. 268, 26712-26718), that the NH2-terminal domain is phosphorylated. In addition, we unexpectedly found an endogenous component, resembling 92-kDa type IV collagenase, that co-purified with L-29 and slowly digested the R-domain. Hence, L-29 is a substrate for bacterial and tissue collagenases even though the R-domain is non-collagenous. Moreover, the co-purification suggests a non-enzymatic interaction between 92-kDa collagenase and L-29.
Highlights
Primary Structure ofthe Soluble LactoseBinding Lectin L-29 from Rat andDog and Interaction of Its Non-collagenousProline, Glycine, Tyrosine-rich Sequence with Bacterial and Tissue Collagenase*
A lactose-bindinglectin from rat lung(RL-29)and a L-29’ is a member of the soluble lactose-binding (S-Lac) related lectin fromMadin-Darbcyaninkeidney lectins, a family of lectins with calcium-independent affinity (MDCK) cells havebeenanalyzed with theprimary for lactose (Leffler et al, 1989)
For the COOH-terminal peptide the assignment was confirmed by collision induced dissociation (CID)-mass spectrometry of chymotryptic peptides (Fig. 3)
Summary
Primary Structure ofthe Soluble LactoseBinding Lectin L-29 from Rat andDog and Interaction of Its Non-collagenousProline-, Glycine-, Tyrosine-rich Sequence with Bacterial and Tissue Collagenase*. The sequences of eight tryptic peptides, determined by high energy CID mass spectrometry, were identical to sequences, deduced from cDNA, within the COOH-domain (Fig. 1) of rat cBP (Albrandt et al, 1987) (Fig. 3).
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