Acts as an E3 ubiquitin-protein ligase, which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes, and then transfers it to substrates promoting their degradation by the proteasome. Functionally coupled with the E2 ubiquitin-protein ligases UB2D1, UB2D2 and UB2D3. Regulator of EGFR mediated signal transduction; upon EGF activation, ubiquitinates EGFR. Inhibits EGF stimulated MAPK1 activation. Promotes ubiquitination of SRC phosphorylated at 'Tyr-419', has the highest ubiquitin ligase activity among CBL family proteins. In collaboration with CD2AP may act as regulatory checkpoint for Ret signaling by modulating the rate of RET degradation after ligand activation; CD2AP converts it from an inhibitor to a promoter of RET degradation; the function limits the potency of GDNF on neuronal survival. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Phosphorylation at Tyr-341 is necessary and sufficient for the activation of E3 activity. Interacts with Ubiquitin-conjugating enzyme E2 UBE2D2 and UBE2D3. Interacts with EGFR (tyrosine phosphorylated). Interacts with the SH3 domain proteins LYN and CRK. Interacts (via RING-type zinc finger) with TGFB1I1 (via LIM zinc-binding domain 2); the interaction is direct and enhances the E3 activity. Interacts directly with RET (inactive) and CD2AP; dissociates from RET upon RET activation by GDNF which also increases the interaction with CD2AP suggesting dissociation as CBLC:CD2AP complex. Interacts with SRC; the interaction is enhanced when SRC is phosphorylated at 'Tyr-419'. EF-hand-like and Sh2-like domains are required for N-terminal inhibition of E3 activity. The N-terminus 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. The RING-type zinc finger domain mediates binding to an E2 ubiquitin-conjugating enzyme. Phosphorylated on multiple tyrosine residues by SRC. Autoubiquitinated, when phosphorylated at Tyr-341. This protein has one functional calcium-binding site.