Specificity of the interaction between phosphatidylinositol 4,5-bisphosphate and the profilin:actin complex

✍ Scribed by Ingrid Lassing; Uno Lindberg

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 823 KB
• Volume: 37
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240370302

✦ Synopsis

Profilactin, the profi1in:actin complex, which is present in large amounts in extracts of many types of eukaryotic cells, appears to serve as the precursor of microfilaments. It was reported recently that profilactin interacts specifically with phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)Pz) (Lasing and Lindberg: Nantre 3 14:472474, 1985.) The present paper describes in detail the behaviour of profilactin and profilin in the presence of different types of phospholipids and neutral lipids under different conditions. PtdIns(4,5)Pz is the only phospholipid found so far which in the presence of 80 mM KCl and at Ca2' concentrations below M effectively dissociates profilactin with the resulting polymerization of the actin. Phosphatidylinositol 4monophosphate exhibits some activity but phosphatidylinositol is inactive. Both calf spleen profilin and profilin from human platelets form stable complexes with PtdIns(4,5)P2 micelles. PtdIns(4,5)P2 is active also when incorporated together with other phospholipids in mixed vesicles.