Q.51 Which of the following proteins is/are involved in intraflagellar transport?
(A) Microtubules
(B) Myosin
(C) Actin
(D) Kinesin
Intraflagellar Transport Proteins: Kinesin Powers Ciliary Movement
Intraflagellar transport (IFT) is a vital process for building and maintaining cilia and flagella using motor proteins on microtubules. Kinesin drives anterograde transport in this mechanism.
Correct Answer
The protein involved in intraflagellar transport is (D) Kinesin. This motor protein moves IFT particles from the base to the tip of the cilium along microtubules.
Option Breakdown
IFT relies on microtubule-based motors, not actin or myosin systems.
-
(A) Microtubules: These form the axonemal tracks for IFT but function as structural rails, not motor proteins.
-
(B) Myosin: Myosin motors actin filaments for muscle contraction and vesicle transport, unrelated to IFT’s microtubule pathway.
-
(C) Actin: Actin provides cytoskeletal support and works with myosin but plays no direct role in IFT.
-
(D) Kinesin: Kinesin-2 powers anterograde IFT, with dynein handling retrograde movement.
IFT Mechanism
IFT particles assemble at the ciliary base and travel bidirectionally. Kinesin-2 enables tip-directed anterograde transport of axonemal precursors like tubulin. Retrograde return uses dynein-2, ensuring cilium maintenance.
Biological Importance
Defects in IFT proteins like kinesin cause ciliopathies such as polycystic kidney disease. This process supports motility, sensing, and development in eukaryotes.
