Epinephrine opposes insulin action. It works through the β2 adrenergic receptor to elicit the cAMP signaling cascade (Tymoczko3e Fig 13.4; Berg8e Fig. 14.1). The image below is of the hormone-bound, activated form of the β2 adrenergic receptor. The red and blue lines demarcate the boundaries of the outer and inner leaflets of the lipid bilayer, respectively. Recall that one complete turn of an α-helix contains 3.4 residues and is 5.4 Angstroms in length. Using the alpha helix as a ruler and the figure below, choose the best answer that describes the thickness of the lipid bilayer.
It is not 7 or 8 turns, I am wondering how to do this?
The given figure contains two β2 adrenergic receptors (B2ARs) which is a type of G Protein coupled Receptor (GPCR). whereas one receptor contains 7 transmembrane α-helices present in it.
Since one helix contain 3.4 residue, then 7 X 3.4 = 23.8 residues in it and it is 37.8 Angstroms in total length.
So, option 3 is correct one.
Epinephrine opposes insulin action. It works through the β2 adrenergic receptor to elicit the cAMP signaling...
Epinephrine signaling , like that of insulin, is a multi-step pathway with several amplification steps. Identify each of the steps below as either allosteric activation or enzymatic. Abbreviations: Epi (epinephrine), β2AR (β2 adrenergic receptor), R2C2 (subunit composition of protein kinase A where R is the regulatory subunit and C is the catalytic subunit), PDE (cyclic AMP phosphodiesterase), PPase (phosphoprotein phosphatase). One of these is wrong but I don't know which one you can only choose enzymatic or allosteric as the answer...