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 Title: Integrin Alpha Subunit Expression and Cytoplasmic Domain Function Author(s): Muschler, John Leonard Doctoral Committee Chair(s): Horwitz, A., Department / Program: Biochemistry Discipline: Biochemistry Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Biology, Cell Chemistry, Biochemistry Abstract: The $\beta\sb1$ integrins are a family of $\alpha\beta$ heterodimeric cell surface receptors which mediate cell adhesion to molecules of the extracellular matrix (ECM), and also span the membrane and associate with the cytoskeleton via their cytoplasmic domains. By mediating the interaction of the cellular cytoskeleton with the ECM, the $\beta\sb1$ integrins are central to issues of cell migration, proliferation, differentiation, cytoskeletal organization, cell morphology, and the maintenance of tissue architecture and integrity. The focus of this work has been to investigate the expression and function of individual chicken $\beta\sb1$ integrin family members. First, the integrins were affinity purified from various adult chicken tissues to reveal the diversity and differential expression of the chicken $\beta\sb1$ integrins. The purified receptors were then used to immunize mice and generate monoclonal antibodies (mAbs) against the $\alpha$ subunits which distinguish each receptor. Antibodies were generated against two $\alpha$ subunits (i.e. two receptors), and were used to identify these $\alpha$ subunits as homologs of the human $\alpha\sb5$ subunit (a fibronectin receptor) and human $\alpha\sb6$ subunit (a laminin receptor). Also, the cross-reaction with chicken $\alpha$ subunits of antisera specific for the human $\alpha$ subunit cytoplasmic domains revealed conserved sequences, and presumably a conserved function, within each $\alpha$ subunit cytoplasmic domain. Immuno-cytochemistry studies using the anti-$\alpha\sb5$ and anti-$\alpha\sb6$ mAbs revealed: (1) the cell-specific expression of the receptors; (2) the changes in receptor expression during embryonic development; and (3) the localization of the receptors in specific membrane-cytoskeletal junctions. The observed junctional specificity of the receptors suggested a unique recognition between cytoskeletal molecules at each membrane-cytoskeleton junction and the integrin $\alpha$ subunit cytoplasmic domains. We have initiated mutagenesis studies to dissect the function(s) within the $\alpha$ subunit cytoplasmic domains. In addition, we have generated antibodies against an apparently novel integrin-associated cytoskeletal protein complex. These antibodies have permitted investigations of the composition and molecular associations at specific integrin-cytoskeleton junctions, and lead to the identification and characterization of several novel cytoskeletal molecules which are components of these junctions. Issue Date: 1993 Type: Text Description: 181 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1993. URI: http://hdl.handle.net/2142/72357 Other Identifier(s): (UMI)AAI9329116 Date Available in IDEALS: 2014-12-17 Date Deposited: 1993
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