This domain is found in the effector protein SidP present in Legionella longbeachae. SidP functions as a Phosphoinositide-3-phosphatase specifically hydrolyzing Phosphoinositide(3)P, referred to as PI(3)P, and PI(3,5)P2. The domain is inserted into the N-terminal portion of the catalytic domain and is referred to as the appendage or insertion (I) domain [1].

1: Identification and structural characterization of a Legionella phosphoinositide phosphatase. Toulabi L, Wu X, Cheng Y, Mao Y; J Biol Chem. 2013;288:24518-24527. PMID:23843460