S6 Kinase Signaling Pathway

1. S6 Kinase Signaling Pathway S6K1 and S6K2 are members of the AGC kinase family. AGC kinases are known as the serine–threonine kinases. AGC kinases have some structural similarities. They play an important role in regulating some cellular activities including growth, survival and metabolism. In addition to S6Ks, some well-known proteins like PKA, PKG, PKC and Akt are also members of the AGC kinase family. Many data in precious studies show that the mTOR/S6K signaling pathway make a great contribution to many common diseases like cancer, diabetes and obesity, which shows its importance. Although S6K1 and S6K2 have many similarities and S6K1 is much better studied, there are some significant differences in terms of their functions both in vitro and in vivo found in new studies. In the kinase domain, they have about 83% of identity, while in they show lower similarity in N terminus and C-terminal domain. S6Kα2 is one of isoforms of S6K1. It is a well-described protein with 502 amino acids which is around 70kD. However, there is another isoform named S6Kα1 with an additional 23 N-terminal amino acids and it is around 85 kD. Even if the smaller isoform p70-S6K1 predominantly stay at the cytosol, it is considered that p85-S6K1 is likely to locate at the nucleus. This assumption is based on the presence of an NLS (nuclear localization sequence) within the N terminal extension of p85-S6K1. In addition to S6K1, S6K2 also has several isoforms. https://www.creative-diagnostics.com/s6-kinase-signaling-pathway.htm