ribosome(redirected from P (peptidyl) site)
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A granule of ribonucleoprotein, 120-200 Ǻ in diameter, that is the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs.
Synonym(s): Palade granule
ribosome/ri·bo·some/ (ri´bo-sōm) any of the intracellular ribonucleoprotein particles concerned with protein synthesis; they consist of reversibly dissociable units and are found either bound to cell membranes or free in the cytoplasm. They may occur singly or occur in clusters (polyribosomes).riboso´mal
A structure composed of RNA and protein, present in large numbers in the cytoplasm of living cells and serving as the site for assembly of polypeptides encoded by messenger RNA.
ri′bo·so′mal (-sō′məl) adj.
Etymology: ribose + Gk, soma, body
an organelle composed of RNA and protein that functions in the synthesis of protein. Ribosomes interact with messenger RNA and transfer RNA to link amino acid into a polypeptide chain in a sequence determined by the sequence of nucleotides in the messenger RNA. Ribosomes may exist singly, in clusters as polysomes, or attached to the "rough" endoplasmic reticulum. See also translation.
A granule of ribonucleoprotein, 120-150 Å in diameter, which is the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs.
ribosomeA spherical cell ORGANELLE made of RNA and protein which is the site of protein synthesis in the cell by linking amino acids into chains. Ribosomes may be free or may be attached to the endoplasmic reticulum. During translation, ribosomes attach to MESSENGER RNA molecules and travel along them, synthesizing polypeptides as they go.
ribosomea small particle (not an ORGANELLE) found in the cytoplasm of all cells, composed of protein and RIBOSOMAL RNA. Each ribosome is composed of two subunits of different sizes which sediment at different rates during centrifugation (see ULTRACENTRIFUGE). PROKARYOTES have ribosome with 70 S size and mass; EUKARYOTES have larger ribosomes with 80 S size and mass. Ribosomes bind to the 5′ end of MESSENGER RNA (see POLYNUCLEOTIDE CHAIN) and travel towards the 3′ end, with TRANSLATION and POLYPEPTIDE synthesis occurring as they go along. Frequently several ribosomes are attached to one piece of mRNA, forming a POLYRIBOSOME.
Palade,George Emil, Romanian-U.S. cell biologist and Nobel laureate, 1912–.
Palade granule - a granule of ribonucleoprotein, the site of protein synthesis from aminoacyl-tRNAs as directed by mRNAs. Synonym(s): ribosome
Weibel-Palade bodies - see under Weibel
ribosomecell organelle; granule formed of ribonucleoprotein; site of protein synthesis, under influence of nuclear m-RNA
ribonucleoprotein particles concerned with protein synthesis; they consist of two, one large and one small, reversibly dissociable units (called also 50S and 30S subunits) that are found either bound to cell membranes, particularly rough endoplasmic reticulum, or free in the cytoplasm. They may occur singly or in clusters, called polyribosomes or polysomes, which are ribosomes linked by mRNA and are actively engaged in protein synthesis.
ribosome binding site
a nucleotide sequence near the 5′ terminus of mRNA required for binding of mRNA to the small ribosomal subunit. Called also Shine-Dalgarno sequence.