Cbl-c: Proteins and Enzymes

Cbl-c is also known as signal transduction protein CBL-C, SH3-binding protein CBL-C, CBL-3, and RING finger protein 57. Cbl proteins are a family of ubiquitin protein ligases (E3s) that negatively regulate signaling by targeting activated tyrosine kinases for degradation. Cbl-c (a.k.a. Cbl-3) is the most recently cloned member of the Cbl proteins and is expressed only in epithelial cells (the other Cbl proteins are ubiquitously expressed). Cbl-c, like the other mammalian Cbl proteins, can ubiquitinate the activated EGFR and target it for degradation. Cbl-c knock out mice show no obvious phenotype. Thus, the physiological role of Cbl-c is not known