The N-terminal predicted helical stretch of the insulin receptor tyrosine kinase substrate p53 (IRSp53) is an evolutionary conserved F-actin bundling domain involved in filopodium formation. The domain has been named IMD after the IRSp53 and missing in metastasis (MIM) proteins in which it occurs. Filopodium-inducing IMD activity is regulated by Cdc42 and Rac1 and is SH3-independent [1].

1: A novel actin bundling/filopodium-forming domain conserved in insulin receptor tyrosine kinase substrate p53 and missing in metastasis protein. Yamagishi A, Masuda M, Ohki T, Onishi H, Mochizuki N; J Biol Chem 2004;279:14929-14936. PMID:14752106