Human;Mouse;Rat;Hamster;Monkey
IQGAPs are scaffolding proteins involved in mediating cytoskeletal function. They contain multiple protein interaction domains and bind to a growing number of molecules including actin, myosin light chain, calmodulin, E-cadherin, and β-catenin. Through their GAP-related domains, they bind the small GTPases Rac1 and cdc42. IQGAPs lack GAP activity, however, and regulate small GTPases by stabilizing their GTP-bound forms. Research studies have shown that the function and distribution of the IQGAP proteins widely vary. IQGAP1 is ubiquitously expressed and has been found to interact with APC and the CLIP170 complex in response to small GTPases, promoting cell polarization and migration. Additional research studies have suggested that IQGAP1 could play a part in the invasiveness of some cancers. IQGAP2, which is about 60% identical to IQGAP1, is expressed primarily in liver, but lower levels have been detected in the prostate, kidney, thyroid, stomach, and testis. Research studies have shown that IQGAP2 displays tumor suppressor properties. Less is known about the function of IQGAP3, but this protein is present in the lung, brain, small intestine, and testis and is only expressed in proliferating cells, suggesting a role in cell growth and division.
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