Human ITGAM (Integrin alpha M subunit) is a 127kDa (predicted) glycoprotein, a member of the Integrin family of proteins. The Integrin family proteins are heterodimeric transmembrane receptors composed of an alpha and a beta subunit. The Integrin alpha M subunit, also known as MAC-1 alpha subunit or CD11b, combines with the Integrin beta 2 subunit (CD18) to form the non-covalent heterodimer Integrin alpha M/ beta 2, also known as MAC-1 and complement receptor type 3 (CR3).