An interaction between alpha-actinin and the beta 1 integrin subunit in vitro.
A number of cytoskeletal-associated proteins that are concentrated in focal contacts, namely alpha-actinin, vinculin, talin, and integrin, have been shown to interact in vitro such that they suggest a potential link between actin filaments and the membrane. Because some of these interactions are of low affinity, we suspect the additional linkages also exist. Therefore, we have used a synthetic peptide corresponding to the cytoplasmic domain of beta 1 integrin and affinity chromatography to identify additional integrin-binding proteins. Here we report our finding of an interaction between the cytoplasmic domain of beta 1 integrin and the actin-binding protein alpha-actinin. Beta 1-integrin cytoplasmic domain peptide columns bound several proteins from Triton extracts of chicken embryo fibroblasts. One protein at approximately 100 kD was identified by immunoblot analysis as alpha-actinin. Solid phase binding assays indicated that alpha-actinin bound specifically and directly to the beta 1 peptide with relatively high affinity. Using purified heterodimeric chicken smooth muscle integrin (a beta 1 integrin) or the platelet integrin glycoprotein IIb/IIIa complex (a beta 3 integrin), binding of alpha-actinin was also observed in similar solid phase assays, albeit with a lower affinity than was seen using the beta 1 peptide. alpha-Actinin also bound specifically to phospholipid vesicles into which glycoprotein IIb/IIIa had been incorporated. These results lead us to suggest that this integrin-alpha-actinin linkage may contribute to the attachment of actin filaments to the membrane in certain locations.
Otey
C A
CA
Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599.
Pavalko
F M
FM
Burridge
K
K
D000185:Actinin / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002846:Chromatography, Affinity; D003598:Cytoskeletal Proteins / Q000302:isolation & purification / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005895:Gizzard, Avian / Q000378:metabolism; D015151:Immunoblotting; D016023:Integrins / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis; D010743:Phospholipids / Q000378:metabolism; D016596:Vinculin
D003598:Cytoskeletal Proteins; D016023:Integrins; D046911:Macromolecular Substances; D010455:Peptides; D010743:Phospholipids; D000185:Actinin; D016596:Vinculin