Subclasses within structural class 3
| Code | Subclass | Examples | |
|---|---|---|---|
| 3.1 | Receptors with intrinsic tyrosine kinase (TK) activity | ||
| e.g., single-subunit TK receptors with extracellular Ig domains; single-subunit TK receptors without extracellular Ig domains; multiple-subunit TK receptors formed by posttranslational cleavage | 3.1 3.1 3.1 | PDGF EGF INS | |
| Trk receptors for neurotrophins | 3.1 | NT1 | |
| 3.2 | Non-enzyme–containing receptors associating with extrinsic tyrosine kinase | ||
| This includes a wide range of receptor types including: (a) receptors that use JAK-type kinases; (b) receptors that associate with other tyrosine kinases, and (c) tyrosine-kinase-associated receptors with the ligand-binding subunit membrane anchored by a glycolipid, such as that for ciliary neurotrophic factor. These receptors are multisubunit, with a ligand-specific α subunit and a subunit type for signal transduction (for examples see Jing et al., 1996; Kleinet al., 1997) | 3.2 3.2 3.2 3.2 3.2 3.2 | IL1 GH INF CNTF GDNF NTN | |
| 3.3 | Receptors with serine/threonine kinase activity | ||
| e.g., receptors for transforming growth factor β | 3.3 | TGF | |
| 3.4 | Intrinsic cyclase receptors | ||
| e.g., receptors with guanylate cyclase activity | 3.4 | ANP | |
(enzyme-associated single transmembrane domain receptors)