※ RIPK family introduction

    RIPK (Receptor-interacting protein kinase) are a group of serine/threonin protein kinases. Five members have been identified in human genome. RIPKs share a conserved kinase domain. RIPK1contain a C-terminal death domain and RIPK2 contains a caspase activation and recruitment domain (CARD). RIPK4 and RIPK5 contain a C-terminal ankyrin repeats (ANK) domains. The C-terminal region of RIPK3 is unique and diverse from other members. RIPK1 is designated as "receptor-interacting" protein. RIPK1 can bind to several death receptors via its deat domain. RIPK1 is expressed in many tissues and the expression is important for T-cell survival, studies show that lacking of RIPK1 will lead to the apoptosis in lymphoid tissue. RIPK2 plays an important in activation of p38 MAPK in the stressed heart. In addition, RIPK2 is also involved in regulation of the NF-kB signaling pathway. RIPK3 can mediate the activation of NF-kB as well and moreover, RIPK3 can directly interact with glycogen phosphorylase (PYGL), glutamate dehydrogenase 1 (GLUD1) and glutamate ammonia ligase (GLUL), and enhance its enzymatic activity. Overexpression of RIPK4 will cause the activation of NF-kB and JNK signaling and overexpression of RIPK5 will lead to cell death (1).

Reference
1. Zhang, D., Lin, J. and Han, J. (2010) Receptor-interacting protein (RIP) kinase family. Cell Mol Immunol, 7, 243-249. PMID: 20383176