※ STKR family introduction

    STKR are serine/threonine kinase receptor comprising two subfamily, TGFb receptors and activin receptors. TGFb receptors contain different isoforms which are homo- or heterodimeric. The mediate the interaction between ligand and receptor. TGFb receptors are expressed in diverse tissues, including heart, liver, kidney, brain and testes. TGFb receptor can be further classified into three subclasses from type1 to type3. Abnormal expression of TGFb receptor leads to renal fibrosis which will result in kidney disease. Diabetes is also found to be associated with TGFb receptor (1). Another subfamily is activin receptors, which are characterized by its feature to bind activin. The activin receptors contain a transmembrane domain and a hydrophilic Cys-rich ligand-binding domain (2).

Reference
1. Wikipedia annotation: TGF beta receptors
2. Wikipedia annotation: Activin receptor