Enables GTPase activator activity and phorbol ester receptor activity. Acts upstream of or within oculomotor nerve formation and positive regulation of GTPase activity. Is expressed in several structures, including central nervous system; digestive system; integument; pharyngeal arch; and testis. Used to study Duane retraction syndrome. Human ortholog(s) of this gene implicated in Duane retraction syndrome. Orthologous to human CHN1 (chimerin 1).