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 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.
Mesh Terms:
Amino Acid Sequence, Animals, Base Sequence, Breast Neoplasms, Carrier Proteins, Cell Line, Cloning, Molecular, Cysteine, DNA, Female, Gene Library, Glycoproteins, Humans, Milk, Human, Molecular Sequence Data, Monocytes, Multigene Family, Oligodeoxyribonucleotides, Receptors, Cell Surface, Receptors, Immunologic, Receptors, Scavenger, Recombinant Proteins, Sequence Homology, Amino Acid, Transfection, Tumor Cells, Cultured
J. Biol. Chem.
Date: Jul. 05, 1993
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