Which Motor Protein Transports Cargo Along Microtubules?

Kinesin and dynein are the key motor proteins for intracellular transport on microtubules, making both correct in standard biology contexts, though exam options often highlight kinesin primarily. This article breaks down the MCQ for biology students preparing for exams like NEET or CSIR NET.

Question Breakdown

The query asks: “Which of the following motor proteins is involved in intracellular transport along microtubules?” Options: 1. Myosin, 2. Kinesin, 3. Dynein, 4. Both Myosin and Dynein.​

Correct Answer

3. Dynein and 2. Kinesin are both involved, but given the options, 4. Both Myosin and Dynein is incorrect as myosin does not use microtubules primarily. Standard answer is often 2. Kinesin or both 2 and 3, with kinesin as anterograde transport leader.

Option Explanations

Myosin (Option 1)

Myosin moves along actin filaments, not microtubules, powering muscle contraction and vesicle transport near the cell cortex. It hydrolyzes ATP for actin-based motility, irrelevant to microtubule tracks.

Kinesin (Option 2)

Kinesin is a plus-end directed motor protein that transports vesicles, organelles, and mRNA toward the cell periphery along microtubules. Conventional kinesin-1 exemplifies anterograde intracellular transport using ATP hydrolysis in 8-nm steps.

Dynein (Option 3)

Dynein is a minus-end directed motor moving cargo toward the microtubule-organizing center, aiding retrograde transport and cilia/flagella beating. Cytoplasmic dynein partners with dynactin for stability in long-distance vesicular trafficking.

Both Myosin and Dynein (Option 4)

Incorrect—myosin operates on actin, not microtubules, while dynein does. This option mixes unrelated proteins; true microtubule motors are kinesin and dynein.

Key Functions Table

Microtubule transport ensures efficient intracellular logistics, vital for neuronal axons and mitosis.