PROSITE documentation PDOC01050

Long hematopoietin receptor, single chain family signature

A number of receptors for lymphokines, hematopoietic growth factors and growth hormone-related molecules have been found to share a common binding domain. These receptors are designated as hematopoietin receptors [1,2] and the corresponding ligands as hematopoietins. Further, hematopoietins have been subdivided into two major structural groups: Large/long and small/short hematopoietins.

Several receptor chains for large hematopoietins are structurally related such that their extracellular parts strictly contain the 200 amino-acids hematopoietin domain, duplicated in the thrombopoietin receptor and in avian prolactin receptors. This subgroup of receptor chains contains:

• Growth hormone receptor (GHR).
• Prolactin receptor (PRLR).
• Erythropoietin receptor (EPOR).
• Thrombopoietin receptor (TPOR).

A schematic representation of the structure of these receptors is shown below:

 +----------------------------------------xxxxxxx-------------------------+
 | C C       C  C  Extracellular          XXXXXXX       Cytoplasmic       |
 +-|-|-------|--|-------------------------xxxxxxx-------------------------+
   | |       |  |                      Transmembrane
   +-+       +--+

These receptor chains are single components of receptors that homodimerize upon binding of the cognate cytokine, following the structural model described for the growth hormone-receptor complex [3].

We have used one pattern to detect this family. The motif is located in the carboxy-terminal part of the 200 amino acid hematopoietin domain.