Chapter Three ID Terms

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Chapter Three ID Terms
2015-02-05 11:34:40
Test One
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  1. molecular chaperones
    Special proteins that assist in protein folding by binding to partly folded polypeptide chains and helping them progress along the most energetically favorable folding pathway ; they prevent the temporarily exposed hydrophobic regions in the newly synthesized protein chains from associating with each other to form protein aggregates
  2. Src protein kinase
    Functions in signaling pathways inside vertebrate cells; has three domains—SH2 and SH3 domains, which have regulatory roles, while the C-terminal domain is responsible for the kinase catalytic activity
  3. Protein families
    Proteins that are grouped together due to having an amino acid sequence and 3D conformation resemblant of one another
  4. Homeodomain
    a class of DNA-binding domains in a pair of proteins from two organisms separated by more than a billion years of evolution
  5. paralogs
    Proteins that evolved to perform somewhat different functions in the same organisms
  6. orthologs
    Corresponding proteins in different organisms
  7. protein modules
    A subset of protein domains that are mobile; they have versatile structure
  8. SH2 domain
    A module that functions in protien-protein interactions and binds the protiens containing it to a second protein that has a phosphorylated tyrosineside chain in a specific amino acid sequence context
  9. Linkage
    The effects of ligand binding on a protein and its affecting of another region- coupled: when two ligands prefer to bind to the same conformation of an allosteric protein, thus increasing the affinity of the protein for the other- uncoupled: if two ligands prefer to bind to different conformations of the same protein ; binding of the first ligand decrease affinity fo the protein for the second ligand
  10. Ras protein
    A GTPase that plays an important role in cell signaling. In its GTP-bound form, it is active and stimulates a cascade of protein phosphorylations in the cell. Most of the time, it is inactive with GDP bound. It becomes active when it echanges its GDP for a GTP molecule in response to etraceullular signals
  11. EF-Tu protein
    • An abundant molecule that serves as an elongation factor in protein synthesis, loading each aminoacyl tRNA molecule onto the ribosome
    • The tRNA forms a tight complex with the GTP bound EF-Tu. In this complex, the amino acid attached to the tRNA is improperly positioned for protein synthesis. The tRNA can transfer its amino acid only after the GTP bound to EF-Tu is hydrolyzed on the ribosome, allowing the EF-Tu to dissociate.
    • Since the GTP hydrolysis is triggered by a proper fit of the tRNA to the mRNA molecule on the ribosome, the EF-Tu serves as a factor that discriminates between correct and incorrect mRNA-tRNA pairings
  12. scaffold proteins
    Link together a set of activating, inhibiting, adaptor, and substrate proteins at a specific location in the cell ; allow cells to compartmentalize reactions even in the absence of membrane; some can hold their substrate or link the unstructured regions, tethering the proteins together