Subtopic: Fundamentals of Cell structure and signaling
Question Statement:
Which of the following proteins is/are involved in intraflagellar transport?
Options:
(A) Microtubules
(B) Myosin
(C) Actin
(D) Kinesin
Official Answer Key:
A;D
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2025 Q.51)**
**1. Governing Concept**:
- **Topic**: Cell Biology & Cilia/Flagella Intraflagellar Transport (IFT)
- Intraflagellar transport (IFT) is a specialized bidirectional motility mechanism required for cilia/flagella assembly and maintenance:
- **Anterograde Transport (base to tip)**: Powered by **Kinesin-2** motor complexes transporting IFT trains along doublet microtubules.
- **Retrograde Transport (tip to base)**: Powered by **Cytoplasmic Dynein-2 (IFT Dynein / dynein 1b)** returning turnover components to the cell body.
**2. Option Analysis**:
- **Option (A) [Kinesin-2] is CORRECT**: The principal anterograde motor driving intraflagellar transport toward the ciliary tip.
- **Option (B) [Myosin II] is INCORRECT**: Actin-based motor involved in muscle contraction and cytokinesis, not ciliary axoneme transport.
- **Option (C) [Kinesin-1 (Conventional Kinesin)] is INCORRECT**: Transports axonal vesicles and organelles in the cytoplasm, not ciliary IFT.
- **Option (D) [Cytoplasmic Dynein-2] is CORRECT**: The canonical retrograde motor responsible for moving IFT complexes from the tip back to the base of flagella.
**3. Final Answer**:
- **Correct Options**: **A, D**
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