#Question id: 1257
#Unit 4. Cell Communication and Cell Signaling
Following statements are regarding to protein kinase A which phosphorylates multiple intracellular target proteins expressed in different cell types.
A. Inactive PKA is a tetramer consisting of two regulatory (R) subunits and two catalytic (C) subunits.
B. Each R subunit contains a pseudo-substrate domain whose sequence resembles that of a peptide substrate and binds to the active site in the catalytic domain but is not phosphorylated; thus the pseudo-substrate domain inhibits the activity of the catalytic subunits.
C. active PKA is turned off by binding of cAMP Each R subunit has two distinct cAMP-binding sites, called CNB-A and CNB-B.
D. Binding of cAMP by an R subunit of PKA occurs in a cooperative fashion; that is, binding of the first cAMP molecule to CNB-B increases the Kd for binding of the second cAMP to CNB-A. Thus small changes in the level of cytosolic cAMP can cause proportionately large changes in the number of dissociated C subunits and, hence, in cellular kinase activity.
Which of the following statements are incorrect?
#Question id: 5809
#Unit 8. Inheritance Biology
Based on the physiological adaptation theory, bacterial populations that had not been exposed to T1 infection:
#Question id: 285
#Unit 1. Molecules and their Interaction Relevant to Biology
About how many nucleosomes could be made from a DNA strand consisting of 1000 base pairs?
#Question id: 28942
#Unit 7. System Physiology – Animal
Which of the following tripeptide hormones, stimulates the secretion of TSH by thyrotropes in anterior pituitary?
#Question id: 5829
#Unit 8. Inheritance Biology
Transitions are base pair substitutions where: