#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: 28360
#Unit 5. Developmental Biology
#Question id: 26399
#Unit 3. Fundamental Processes
The origin enters S phase in the condition of a prereplication complex, which contains
#Question id: 10366
#Unit 6. System Physiology – Plant
Cyanobacteria can fixes nitrogen in an anaerobic conditions. Which of the following statements about heterocyst which is specialized cell of blue-green algae is incorrect?
#Question id: 3616
#Unit 8. Inheritance Biology
If the parents are AO and BO genotypes for the ABO blood group, their children could include which of the following genotypes?