Studies on the Transmembrane Signaling of β1 Integrins BY

Armulik, A. 2000. Studies on the transmembrane signaling of β1 integrins. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 963. 92 pp. Uppsala. ISBN 91-544-4832-1. Integrins are heterodimeric cell surface receptors, composed of an α and a β subunit, mainly for binding extracellular matrix proteins. Integrin subunit β1 can combine with at least 12 α subunits and thus form the biggest subfamily within the integrin family. In this thesis, functional properties of the splice variant β1B, and the effects of several mutations in the cytoplasmic tail of integrin subunit β1A were studied. In addition, the border between the transmembrane and cytoplasmic domains of several integrin subunits was determined. The β1B splice variant has been reported to have a dominant negative effect on functions of β1A integrins. In this study, it was studied if the expression of β1B had similar negative effects on the αvβ3 integrin functions since the β3 subunit is structurally similar to β1A. The β1B subunit was expressed in an integrin β1-deficient cell line and it was found that the presence of β1B does not interfere with adhesion or signaling of endogenous αvβ3