P-site

The P-site (for peptidyl) is the second binding site for t-RNA in the ribosome. The other two sites are the A-site (aminoacyl), which is the first binding site in the ribosome, and the E-site (exit), which is the third and final binding site in the ribosome. L27 is located at the P-site as shown by affinity labeling. The P-site during translation holds the t-RNA which is linked to the growing polypeptide chain. When a stop codon is reached ending translation, the peptidyl-tRNA bond of the t-RNA located in the P-site is cleaved releasing the newly synthesized protein.

References

1. A.P. Czernilofsky et al., Proc.Natl.Acad.Sci. USA, Vol 71, pp 230–234, 1974, and FEBS Lett., Vol 63, pp 283–286, 1976.

Ribosome

The ribosome (/ˈraɪbəˌsoʊm, -boʊ-/) is a complex molecular machine found within all living cells, that serves as the site of biological protein synthesis (translation). Ribosomes link amino acids together in the order specified by messenger RNA (mRNA) molecules. Ribosomes consist of two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a polypeptide chain. Each subunit is composed of one or more ribosomal RNA (rRNA) molecules and a variety of proteins. The ribosomes and associated molecules are also known as the translational apparatus.

The sequence of DNA, which encodes the sequence of the amino acids in a protein, is copied into a messenger RNA chain. It may be copied many times into RNA chains. Ribosomes can bind to a messenger RNA chain and use its sequence for determining the correct sequence of amino acids. Amino acids are selected, collected, and carried to the ribosome by transfer RNA (tRNA) molecules, which enter one part of the ribosome and bind to the messenger RNA chain. It is during this binding that the correct translation of nucleic acid sequence to amino acid sequence occurs. For each coding triplet in the messenger RNA there is a distinct transfer RNA that matches and which carries the correct amino acid for that coding triplet. The attached amino acids are then linked together by another part of the ribosome. Once the protein is produced, it can then fold to produce a specific functional three-dimensional structure although during synthesis some proteins start folding into their correct form.

Site

Site may refer to:

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Sitež

Sitež is a settlement in the Municipality of Majšperk in northeastern Slovenia. It lies in the Haloze Hills on the regional road from Majšperk to Žetale. The area is part of the traditional region of Styria. It is now included with the rest of the municipality in the Drava statistical region.

References

External links

Website

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