Mouse macrophage beta subunit (CD11b) cDNA for the CR3 complement receptor/Mac-1 antigen

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• Leukocyte cell adhesion receptors, including the LFA-1/Mac-1/p150,95 group (integrin beta 2), play critical roles in immune responses.
• The Mac-1 subunit (CD11b) is a component of macrophage activation antigen 1 (Mac-1), also known as complement receptor type 3 (CR3).

Purpose of the Study:

• To clone and sequence the complementary DNA (cDNA) for the common beta Mac-1 subunit (CD11b) in mice.
• To analyze the structural characteristics and evolutionary conservation of the mouse Mac-1 subunit.

Main Methods:

• Isolation of clones from cDNA libraries derived from J774 macrophage and WEHI-3B myelomonocytic tumor cells.
• Sequencing of the 2422 base pair (bp) cDNA to determine the protein structure and identify conserved domains.

Main Results:

• The mouse beta Mac-1 subunit cDNA sequence was obtained, coding for a 771 amino acid protein with distinct functional domains.
• High sequence identity (81%) was observed between the mouse and human beta Mac-1 subunits, particularly in the transmembrane and cytoplasmic domains.
• Conserved N-linked glycosylation sites and cysteine residues indicate conserved structural motifs characteristic of integrin beta subunits.

Conclusions:

• The cloning and sequencing of the mouse beta Mac-1 subunit provide a molecular basis for understanding its role in cell adhesion and immune functions.
• Highly conserved transmembrane and cytoplasmic domains suggest conserved mechanisms in Mac-1-mediated processes, such as iC3b-triggered phagocytosis.
• The findings highlight the evolutionary conservation of integrin beta subunit structure and function.