Final answer:
The question seems to be conflating microtubule (MT) structure with ATP-synthase components. While 'B subunits' might indicate beta-tubulin in microtubules, the ATP-synthase complex involves Fob as a non-rotating part that connects F1 to the ring of Foc subunits, crucial for ATP production.
Step-by-step explanation:
The student has asked about the exposed end of the MicroTubule (MT) that has B subunits on the edge, possibly referring to the structure involved in cell processes like ATP synthesis. Neither MT nor B subunits are directly implicated in ATP synthesis; instead, ATP-synthase plays a crucial role here. The F1Fo ATP-synthase complex is essential for ATP production in cells, and the query seems to be describing components of this complex. The Fo part of ATP-synthase, specifically the ring of c subunits (Foc), is where the B subunit (Fob) comes into play.
The Fob subunit binds the F1 and Fo portions together and is part of the mechanism preventing the F1 portion from rotating. The Foc subunits, arranged in a circle, include an acidic asp residue which interacts with a peptide-NH3 from the Fob subunit, facilitating the mechanical tension required for its function. However, the exposed end of MT with B subunits is actually not a direct reference in the ATP-synthase structure but could be a confusion with beta-tubulin at the plus end of a microtubule, which is a part of cytoskeletal microtubules and irrelevant to ATP-synthase.