Embedded in the plasma membrane?

Question

A. peptide hormone receptors

B. Ca++ channels

C. Glucose transporters in insulin-sensitive cells.

D. Microtubules

E. Adenylate cyclase catalysis of cAMP synthesis

Answer 1

A, B and C are definitely true.  D is usually located in the cytoplasm and E is located on the cytoplasmic side of the cell membrane.  It is a part of the receptor-2nd messenger complex so some consider it part of the membrane receptor. Although the enzyme adenylate cyclase is not strictly membrane bound.  

Answer 2

Peptide hormone receptors are located on cell surfaces - so that's a pretty strong candidate answer.  

Likewise - Calcium channels are found in the plasma membrane and play a role in maintaining the electrical charge of the cell.

Glucose transporter proteins

Glucose transporters also are part of the plasma membrane

Microtubules are generally cytoplasmic and give rise to the cytoskeleton and are involved in cellular processes such as mitosis.  They also are associated with movement related structures such as flagellae and cilia in eukaryotes.

Adenylate cyclase is a transmembrane protein.

Thus - of the choices provided - I would conclude that 'D' microtubles are NOT embedded in the plasma membrane.

Good luck - and keep studying science!

Answer 3

All except D are embedded in the plasma membrane.