EAT-20, a novel transmembrane protein with EGF motifs, is required for efficient feeding in Caenorhabditis elegans

The pharynx of Caenorhabditis elegans is a neuromuscular organ responsible for feeding, concentrating food by its pumping movement. A class of mutants , the eat mutants, are defective in this behavior. We have identified a nov el eat gene, eat-20, encoding a unique transmembrane protein with three EGF motifs. Staining with a specific polyclonal antibody reveals that EAT-20 i s expressed predominantly in the pharyngeal muscles and a subset of neurons . Some hypodermal cells also express EAT-20, eat-20 mutant animals are star ved, have smaller brood sizes, and have prolonged egg-laying periods. The s tarvation apparently results from pharyngeal pumping defects, including a r educed pumping rate and "slippery pumping," in which the contents of the ph arynx sometimes move rostrally. However, electrical activity of eat-20 muta nts appears normal by electropharyngeogram.