This family of proteins is found in eukaryotes, and are typically between 288 and 332 amino acids in length. Family members include the Saccharomyces cerevisiae Chs7, an integral membrane protein located in the ER which is directly involved in chitin synthesis through the regulation of chitin synthase III (CSIII) activity. In the absence of CHS7 gene product, Chs3p, but not other secreted proteins, is retained in the ER, leading to a severe defect in CSIII activity and consequently, to a reduced rate of chitin synthesis. In addition, chs7 null mutants show the yeast phenotypes associated with a lack of chitin: reduced mating efficiency and lack of the chitosan ascospore layer, clear indications of Chs7p function throughout the S. cerevisiae biological cycle. Hence, Chs7 is involved in the regulation of CSIII activity by controlling Chs3p export from the ER [1, 2].

1: Role of chitin synthase genes in Fusarium oxysporum. Martin-Udiroz M, Madrid MP, Roncero MI; Microbiology. 2004;150:3175-3187. PMID:15470098

2: Chs7p, a new protein involved in the control of protein export from the endoplasmic reticulum that is specifically engaged in the regulation of chitin synthesis in Saccharomyces cerevisiae. Trilla JA, Duran A, Roncero C; J Cell Biol. 1999;145:1153-1163. PMID:10366589