|Protein Name||40S ribosomal protein S6|
|Protein Existence Status||Unreviewed: Protein predicted|
|Protein Function||thirty four members of ribosomal protein family can be found in all domains of life; This group includes 15 proteins of the small (S2 S5, S7 S15, S17, and S19) and 19 proteins of the large (L1 L6, L10 L15, L18, L22 L24, L29, L30, and L7ae) ribosomal subparticles; specifically bind to nucleic acids other than rRNA; have a growth promoting activity; RP S3 possesses DNA modifying enzymatic activities; ribosomal proteins are essential for ribosome assembly and optimal function; required in ribosome biogenesis and translational fidelity and is also a central controller of ribosome transit between non-rotated and rotated conformational states|
|Biochemical Properties||Eukaryotic ribosomes are made up of four different RNA molecules and of 79 different proteins; basic proteins, in accordance with their main function, which consists in the specific interaction with the ribosomal RNAs; Regions of basic charge within RPs enable them to interact with the negatively charged phosphate groups of the nucleic acids; The isoelectric points of S and L rat RPs range between 7 and 13.5; Basic charges are not equally distributed but tend to occur in clusters of three or more adjacent amino acids, which are scattered over different regions of the sequence. In a small number of RPs (S8, S9, L5, L22, L31, LP0, LP1 and LP2) there are also a few C-terminal clusters of acidic amino acids; Phosphoproteins LP0, LP1 and LP2, as well as RP SA, are the only ribosomal proteins with acidic pI values; majority of ribosomal proteins are packed into β bar rels; α/β sandwiches and other types of structural packing of proteins; half of ribosomal proteins have elongated loops or N and C terminal “tails” which have a considerable intramolecular mobility; loops and tails the contents of positively charged lysines and arginines is two to three times higher than in the globular part of the protein; riboso mal proteins mainly interact with the sugar phosphate backbone of RNA through positively charged residues of the protein chain;|
|Significance in milk||Regulates protein synthesis in lactation compared to pregnanacy; RPL35 regulates beta casein expression; several ribosomal proteins (RPL23A, RPL4 and RPS6) have been associated with milk protein synthesis in mammary gland of lactating cows|
|PTMs||Phosphorylation of RP S6 - Near its C-terminus, RP S6 has five serine residues (positions 235, 236, 240, 244 and 247) that are phosphorylated in a precise order on the protein integrated in the 40S subunit; N-terminal acetylation and methylation|
| Site(s) of PTM(s) |
|Significance of PTMs||S6 phosphorylation is a ubiquitous response when quiescent cells are induced to re-enter the cell cycle; regulates activity of the ribosome;|
|Bibliography||1. Ballesta, J. P., Rodriguez-Gabriel, M. A., Bou, G., Briones, E., Zambrano, R., & Remacha, M. (1999). Phosphorylation of the yeast ribosomal stalk. Functional effects and enzymes involved in the process. FEMS Microbiology Reviews, 23(5), 537–550. https://doi.org/10.1111/j.1574-6976.1999.tb00412.x. |
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4 Thomas, G. (2002). The S6 kinase signaling pathway in the control of development and growth. Biological Research, 35(2), 305–313. https://doi.org/10.4067/s0716-97602002000200022.
5. Jang, C.-Y., Lee, J. Y., & Kim, J. (2004). RpS3, a DNA repair endonuclease and ribosomal protein, is involved in apoptosis. FEBS Letters, 560(1–3), 81–85. https://doi.org/10.1016/S0014-5793(04)00074-2.