| Term | Definition |
| Class I | ligand binding induces monomer dimerization; autophosphorylation of cytoplasmic domain |
| Class II | ligand binding induces active conformation of disulfide crosslinked dimer; autphosphorylation of cytoplasmic domain and IRS |
| Class III | dimer ligand crosslinks monomers; autophosphorylation of cytoplasmic domain |
| SH2 | bind to peptide motifs with phospho-tyrosine |
| PTB | bind to peptide motifs with phopho-tyrosine or tyrosine |
| SH3 | bind to proline rich motifs |
| PH | bind to membranes or membrane proteins |