The Myosin Light Chain-IQGAP Interaction: What is its Function? pp. 139-148
Authors: David J Timson
Abstract: The first members of the IQGAP family of proteins were characterised over 15 years ago. It is now known that these molecules act at the interface between cellular signalling pathways and the actin cytoskeleton. They bind to a diverse range of signalling molecules – including those involved in calcium, GTPase, kinase and growth factor signalling. One intriguing interaction is that between mammalian IQGAP1 and the myosin essential light chain isoform, Mlc1sa. Although this has been demonstrated in vitro, its in vivo role is not known. Indeed, it would be tempting to dismiss it as an experimental artefact, except for the existence of a parallel interaction in the budding yeast, Saccharomyces cerevisae. In this organism, the IQGAP-like protein (Iqg1p) interacts with a myosin essential light chain (Mlc1p). This interaction is critical for the correct execution of cytokinesis. IQGAP-like proteins also play key roles in cytokinesis in other fungi. Recent work implicating mammalian IQGAP1 in cytokinesis may help explain the role of the interaction in higher eukarytotes.