UC San Diego

While many types of enzymes have an actin fold, the ability to polymerize have always been thought to be a defining feature of cytoskeletal actins. Here, I have identified in vivo conditions that cause the yeast glucokinase, Glk1p, to form filaments. This polymerization is highly regulated and readily reversible. It has been argued that phosphotransferases evolutionarily predate actin-fold proteins, such as cytoskeletal actins that do not transfer a phosphate to a substrate. Therefore, the discovery that the actin-fold phosphotransferase, Glk1p, can polymerize argues that cytoskeletal actins evolved from metabolic enzymes that polymerize to form filaments