Cardiotrophin-1 (2. Cardiotrophin-1 receptor)

Gp130-gp190 heterocomplex formation is essential for CT-1 signaling. Analysis of the subsequent activation events revealed that CT-1 induces and utilizes Jak1-, Jak2-, and Tyk2-associated tyrosine kinases, which are in turn relayed by STAT-3 transcription factor and MAPK (ERK1 and –2) signaling pathways. Cross-linking of iodinated CT-1 to the cell surface led to the identification of a third alpha component in addition to gp130 and gp190, with an apparent molecular mass of 80 kDa. Removal of n-linked carbohydrates from the protein backbone of the alpha component resulted in a protein of 45 kDa. These results provide evidence that the CT-1 receptor is composed of a tripartite complex, a situation similar to the high affinity receptor for ciliary neurotrophic factor ^Ref .