ABSTRACT
This chapter discusses the role of β2 integrins in leukocyte adhesion. Molecular cloning of the genes encoding all four β2 integrin proteins has been accomplished. The cytoplasmic tails of the three β2 integrin a subunit proteins do not share significant homology, and this may in part explain their different and distinct distribution in leukocytes, intracellular storage, and functions. The function of the β2 integrin family, like other integrins, is to mediate cell adhesion. Functional regulation of the β2 integrin family leading to increased cell adhesion is known to occur in at least two ways: an upregulation of the quantity of the receptor on the cell surface and activation of the receptor. Several studies have documented that the β2 integrin a subunit cytoplasmic tails are constitutively phosphorylated on their serine and threonine residues. Some other adhesion-mediating receptors on leukocytes are also integrins, such as the β1 family, also known as the VLA antigens.
