Fig. 1. PLCε represents a novel class of PLC. (A) Four classes of mammalian PLC isoforms, rat PLCβ1, human PLCγ1, rat PLCδ1 and PLCε, and C.elegans PLC210 are illustrated. Domains identified include PLC catalytic X and Y domains; C2, Ca²⁺-dependent lipid-binding domain; SH2 and SH3, Src homology 2 and 3 domains; GRF CDC25, GTP/GDP exchange factor domain; and two Ras-binding domains, RA1 and RA2. The percentage identity with PLCε is shown above each domain. (B) Predicted amino acid sequence of the rat PLCε. Domain regions are boxed. (C) Autoradiograph of a western blot stained with anti-FLAG of a COS-7 cell lysate overexpressing PLCε (pCMV-rPLCε-FLAG). Precision molecular weight markers (Bio-Rad Laboratories, Hercules, CA) were used to determine the relative molecular weight.