Cloning and characterization of a human Mac-2-binding protein, a new member of the superfamily defined by the macrophage scavenger receptor cysteine-rich domain

We have purified and sequenced a secreted glycoprotein from both the human breast carcinoma cell line, SK-BR-3, and human breast milk. The native protein binds specifically to a human macrophage-associated lectin known as Mac-2. This Mac-2 binding protein (Mac-2-BP) has an apparent native molecular...

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Veröffentlicht in:The Journal of biological chemistry 1993-07, Vol.268 (19), p.14245-14249
Hauptverfasser: KOTHS, K, TAYLOR, E, HALENBECK, R, CASIPIT, C, WANG, A
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Sprache:eng
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Zusammenfassung:We have purified and sequenced a secreted glycoprotein from both the human breast carcinoma cell line, SK-BR-3, and human breast milk. The native protein binds specifically to a human macrophage-associated lectin known as Mac-2. This Mac-2 binding protein (Mac-2-BP) has an apparent native molecular mass of several million daltons and contains subunits of 85-97 kDa that are very susceptible to proteolysis at a dibasic cleavage site. Western analysis suggests that Mac-2-BP is found in serum, semen, saliva, urine, and tears, in addition to breast milk. The gene encoding Mac-2-BP was cloned from a cDNA bank of a human monocytic cell line, using degenerate PCR primers based on the protein sequence. Recombinant Mac-2-BP was expressed in Cos cells and secreted as a high molecular weight complex. The cDNA clone encodes a mature protein of 567 amino acids, preceded by an 18-amino acid leader. The mature protein contains 16 cysteines and has seven potential N-linked glycosylation sites. The first 106 amino acids represent a domain that is highly similar to an ancient protein superfamily defined by the macrophage scavenger receptor cysteine-rich domain.
ISSN:0021-9258
1083-351X
DOI:10.1016/s0021-9258(19)85233-x