Characterization of macrophage adhesion molecule.

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Macrophage adhesion molecule (MAM) is a key surface protein involved in macrophage adhesion and spreading.
• MAM is abundant on guinea pig macrophages, with an estimated density of 630,000 molecules per cell.

Purpose of the Study:

• To characterize the molecular structure and properties of Macrophage adhesion molecule (MAM).
• To identify potential analogues of MAM in other species.

Main Methods:

• Quantitative binding assays using 125I-labeled monoclonal antibody.
• Isoelectrofocusing to analyze glycopeptide subunits.
• Electrophoresis and reactivity testing with monoclonal antibodies.

Main Results:

• MAM is a heterodimer of gp160 (MAM-alpha) and gp93 (MAM-beta), sensitive to trypsin and plasmin.
• Glycopeptide subunits exhibit microheterogeneity with specific isoelectric points (pI).
• A gp160, gp93 molecule in neutrophils is identical to macrophage MAM; a related heterodimer (gp180,gp93) exists on lymphocytes.

Conclusions:

• Macrophage adhesion molecule (MAM) is structurally and functionally characterized.
• MAM is identified as the guinea pig homologue of human Mo1 and mouse Mac-1, suggesting conserved functions across species.