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Codon, Terminator definition: Any codon that signals the termination of genetic translation (TRANSLATION, GENETIC). PEPTIDE TERMINATION FACTORS bind to the stop codon and trigger the hydrolysis of the aminoacyl bond connecting the completed polypeptide to the tRNA. Terminator codons do not specify amino acids.
Nuclear Localization Signal definition: An amino acid sequence that directs the post-translational transport of a protein to the nucleus. The sequence contains positively charged amino acids such as arginine and lysine.
Nuclear Localization Signals definition: Short, predominantly basic amino acid sequences identified as nuclear import signals for some proteins. These sequences are believed to interact with specific receptors at the NUCLEAR PORE.
Protein Sorting Signals definition: Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.
RNA 3' Polyadenylation Signals definition: Sequences found near the 3' end of MESSENGER RNA that direct the cleavage and addition of multiple ADENINE NUCLEOTIDES to the 3' end of mRNA.
regulation of cell growth by extracellular stimulus definition: Any process whereby external signals modulate the frequency, rate or extent of cell growth, the irreversible increase in size of a cell over time. [GOC:dph]
induction of apoptosis by extracellular signals definition: Any process induced by extracellular signals that directly activates any of the steps required for cell death by apoptosis. [GOC:ai]
induction of apoptosis by intracellular signals definition: Any process induced by intracellular signals that directly activates any of the steps required for cell death by apoptosis. [GOC:ai]
CREB Activation Signaling Pathway definition: The transcription factor CREB binds the cyclic AMP response element (CRE) and activates transcription in response to a variety of extracellular signals including neurotransmitters, hormones, membrane depolarization, and growth and neurotrophic factors. Protein kinase A and the calmodulin-dependent protein kinases CaMKII stimulate CREB phosphorylation at Ser133, a key regulatory site controlling transcriptional activity. Growth and neurotrophic factors also stimulate CREB phosphorylation at Ser133. Phosphorylation occurs at Ser133 via p44/42 MAP Kinase and p90RSK and also via p38 MAP Kinase and MSK1. CREB mutants exhibit deficiencies in spatial learning tasks, while flies overexpressing or lacking CREB show enhanced or diminished learning, respectively. (BioCarta)
Sprouty Regulation of Tyrosine Kinase Signaling Pathway definition: Four different members of the Sprouty protein family block the cellular proliferation and differentiation induced by several different growth factors, including EGF and FGF. One mechanism by which Sprouty proteins inhibit signaling is through binding to Grb-2, a signaling intermediary between the tyrosine kinase growth factors and the Ras/map kinase pathway. Binding of Sprouty to Grb-2 prevents Grb-2 and Sos-1 from interacting with downstream signaling factors that activate Ras and map kinases, including Ras, Raf-1, Mek1, Erk1/2, and downstream transcription factors. The action of Sprouty as an inhibitor of this pathway requires Sprouty phosphorylation and membrane localization at the site of the factors it interacts with. The inhibition of growth factor signaling by Sprouty is specific to the Ras pathway since the PI3 Kinase pathway responsible for cell survival signals from growth factor receptors is not inhibited by Sprouty. Tyrosine kinase activity of growth factor receptors is also not affected. The mechanism by which Sprouty inhibits Ras activation may be by blocking the nucleotide exchange activity of Sos. Sprouty expression is induced by growth factor receptor activation of Ras signaling, provided a self-regulatory feedback inhibition mechanism that regulates growth factor signaling through Ras. In addition to blocking the Ras pathway, Sprouty also induces protein tyrosine phosphatase 1B activity. Activation of PTP1B by Sprouty is responsible for the inhibition of cellular migration that Sprouty causes, but is not involved in regulation of cellular proliferation. While blocking receptor tyrosine kinase signaling, at least one member of the Sprouty family, Sprouty-2, also acts by one mechanism to stimulate EGF receptor signaling. Cbl targets the EGF receptor for tagging with ubiquitin and proteolytic destruction. Sprouty-2 binds to Cbl and blocks the ubiquitination and destruction of the EGF receptor, increasing EGF signaling. (BioCarta)
Nuclear Export Signals definition: Specific amino acid sequences present in the primary amino acid sequence of proteins which mediate their export from the CELL NUCLEUS. They are rich in hydrophobic residues, such as LEUCINE and ISOLEUCINE.