passage 5 related questions Flashcards
What is a second messanger system?
Second messengers are intracellular signaling molecules released by the cell to trigger physiological changes such as proliferation, differentiation, migration, survival, and apoptosis. Secondary messengers are therefore one of the initiating components of intracellular signal transduction cascades.
what are the examples of second messangers?
Examples of second messenger molecules include cyclic AMP, cyclic GMP, inositol trisphosphate, diacylglycerol, and calcium.
How does cAMP acts?
Second messanger cAMP activates protein kinase A (PKA),which can then activates nuclear transcription factor, cAMP response element binding protein (CREB).
CREB exists in two isoforms - one being 327 Amioacids residues
Gylcogen kinase -3 phosphorylates CREB at 115 on a serine residue and PKA phosphorylates at serine at 119
what is isoelectric focusing ?
Isoelectric focusing (IEF) is an electrophoretic technique for the separation of proteins based on their isoelectric point (pI). The pI is the pH at which a protein has no net charge and thus, does not migrate further in an electric field. IEF gels are used to determine the pI of a protein and to detect minor changes in the protein due to post-translational modifications such as phosphorylation and glycosylation.
how does different isoforms of a protein are formed?
different protein isoforms are formed by same gene , but alternative splicing, during which sections of the full transcripts are spliced differently. different combinations of exons can form different isoforms
In phosphorylation exteriments with kinsases, what is the control that needs to be included to eliminate error against autophosphorylations?
the kinases and ATP with out the substrate is used as control.
how is transcriptional activity CREB is assayed ?
percent conversion of chlorampinicol to its acytelaed form is used as an indicator for transcriptional activity of CREB
In other words CREB induces the trancription of the protein enzyme that actylates chlorampinicol. This actylation activity is used indirectly to measure the activity of CREB transcriptional activity
How does AKT get activated?
the diagram shows upstream signalling for AKT activation
what is Akt pathway ?
The Akt Pathway, or PI3K-Akt Pathway is a signal transduction pathway that promotes survival and growth in response to extracellular signals. Key proteins involved are phosphatidylinositol 3-kinase (PI3K) and Akt, or Protein Kinase B.
what are glucogenic aminoacids ?
Amino acids are divided into glucogenic amino acids and ketogenic amino acids. Glucogenic amino acids can enter the Citric Acid Cycle as either pyruvate, α-ketoglutarate, succinyl-CoA, fumarate, or oxaloacetate and used to produce glucose.
how is glucogenic aminoacids converted to glucose?
What is the difference between rate constant and equilibrium constant? k and Keqb
The rate constant is the measure of reaction rate when the concentration of all the reactant are unity. It gives the measure of fastness of a reaction. It is denoted by k
The equilibrium constant is the ratio of rate of forward reaction and rate of backward reaction.
Kc=rate of forward reaction /rate of backward reaction
So
Kc=Kf/Kb
Kf, Kb are the rate constants (k)
what is Arrhenius equation
The Arrhenius equation is a formula for the temperature dependence of reaction rates. The equation was proposed by Svante Arrhenius in 1889,
what is RTK
Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones.
How does RTK get activated ?
When signaling molecules bind to RTKs, they cause neighboring RTKs to associate with each other, forming cross-linked dimers. Cross-linking activates the tyrosine kinase activity in these RTKs through phosphorylation — specifically, each RTK in the dimer phosphorylates multiple tyrosines on the other RTK. This process is called cross-phosphorylation.
