ABSTRACT
This chapter addresses the structural features of integrin cytoplasmic domains and attempts to relate this information to the emerging knowledge regarding their biochemical and biological functions. The active molecular biology studies have provided primary sequences for 13 different integrin α subunits, in many cases with corresponding homologues from several species. The variant forms of α6 and α3 are expressed in a cell-type specific manner and offer another layer of complexity to integrin-specific cellular responses. There are 8 different integrin β subunits that have been identified and sequenced. The cytoplasmic domains of the β1, β3, and β4 subunits have alternatively spliced forms, which potentially may provide additional functional diversity for these integrins. Using equilibrium gel filtration, it was found that a 225-kDa cytoskeletal protein called talin could bind to an integrin complex purified from chicken fibroblasts. A direct interaction between α-actinin and a β2 integrin has also been proposed.
