In an experiment, laboratory animals are subjected to a toxic insult that specifically targets the protein kinesin. Which of the following is most likely to be absent from tissues on histological examination as a result?

Question

In an experiment, laboratory animals are subjected to a toxic insult that specifically targets the protein kinesin.  Which of the following is most likely to be absent from tissues on histological examination as a result?

Quizplus · Accepted Answer

Kinesin is a microtubule associated motor protein whose function is anterograde transport of intracellular vesicles and organelles toward the plus (rapidly growing) ends of microtubules. Kinesin uses energy derived from ATP hydrolysis to move along the microtubule. The plus ends of microtubules typically lie at sites distant from the nucleus; thus, in neurons, kinesin carries vesicles and organelles away from the cell body and toward the nerve terminal. A targeted toxic insult to this protein would be expected to impair anterograde transport resulting in a deficiency of synaptic vesicles at the nerve terminal. (Choice A) The Nissl substance in neurons corresponds to the rough endoplasmic reticulum. (Choice C) The transverse tubule (T-tubule) system is a tubular network located at the junction of the A and I bands of striated myocytes. T-tubules are open to the extracellular space and facilitate the spread of depolarization to the inside of the cell. (Choice D) Desmosomes are protein aggregates that mediate cell-cell adhesion between epithelial cells. (Choice E) Microvilli are small cylindrical extensions of the apical plasma membrane that contain actin thin filaments. Microvilli cover the apical surfaces of intestinal epithelial cells. They do not contain microtubules or microtubule associated proteins. Educational Objective: Kinesin is a microtubule-associated, ATP-powered motor protein that facilitates the anterograde transport of neurotransmitter-containing secretory vesicles down axons to synaptic terminals.

In an Experiment, Laboratory Animals Are Subjected to a Toxic