Induces early B-lineage lymphomas. Is composed of the phosphotyrosine binding (PTB) domain, a short linker region and the RING-type zinc finger. The PTB domain, which is also called TKB (tyrosine kinase binding) domain, is composed of three different subdomains: a four-helix bundle (4H), a calcium-binding EF hand and a divergent SH2 domain (By similarity). This protein is synthesized as a Gag-Cbl polyprotein. This protein has one functional calcium-binding site.