CRCB is a family of bacterial integral membrane proteins with four TMs.. Over expression in E. coli also leads to camphor resistance [1,2].

1: Overproduction of three genes leads to camphor resistance and chromosome condensation in Escherichia coli. Hu KH, Liu E, Dean K, Gingras M, DeGraff W, Trun NJ; Genetics 1996;143:1521-1532. PMID:8844142

2: Phenotypic characterization of overexpression or deletion of the Escherichia coli crcA, cspE and crcB genes. Sand O, Gingras M, Beck N, Hall C, Trun N; Microbiology. 2003;149:2107-2117. PMID:12904550