Cbl is an adaptor protein that binds EGF receptors (or other tyrosine kinases) and SH3 domains, functioning as a negative regulator of many signaling pathways. The N-terminal domain is evolutionarily conserved, and is known to bind to phosphorylated tyrosine residues. The so called N-terminal domain is actually 3 structural domains, of which this is the central EF hand domain.

1: Structure of the amino-terminal domain of Cbl complexed to its binding site on ZAP-70 kinase Meng W, Sawasdikosol S, Burakoff SJ, Eck MJ; Nature 1999;398:84-90. PMID:10078535