|Detection of Human, Mouse, and Rat Ribosomal Protein S6 by Western Blot. Western blot shows lysates of HeLa human cervical epithelial carcinoma cell line, HepG2 human hepatocellular carcinoma cell line, NIH‑3T3 mouse embryonic fibroblast cell line, and Rat‑2 rat embryonic fibroblast cell line. PVDF membrane was probed with 1 µg/mL of Sheep Anti-Human/Mouse/Rat Ribosomal Protein S6 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF5436) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for Ribosomal Protein S6 at approximately 32 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
(40S) Ribosomal protein S6 (rpS6; also Phosphoprotein NP33) is a 32-34 kDa member of the ribsosmal protein S6e family of molecules. It is ubiquitously expressed and involved in the regulation of cell size. Higher eukaryotic ribosomes contain a small (or 40S) and large (or 60S) subunit. The small subunits are composed of one RNA molecule plus more than 30 individual proteins, one of which is rp6S. It is a substrate of both PASKIN and S6 kinase, and when phosphorylated C-terminally, appears to slow the rate of protein synthesis. Notably, the activities of rpS6 are complex, as phosphorylation seems to decrease cell proliferation and glucose utilization on one hand, while increasing cell size on the other. Human ribosomal protein S6 is 249 amino acids (aa) in length. It possesses two acetylated lysines plus six phosphorylated serines. There are three potential splice forms. One contains a four aa substitution for aa 1-46, a second utilizes an alternative start site at Met32, and a third utilizes the same Met32 start site coupled to a substitution of a Gln residue for aa 234-243. Full-length human, mouse and rat rpS6 are identical in their amino acid sequences.