Question:medium
Transport across the nucleus is carried out by all of the following except?
Transport across the nucleus is carried out by all of the following except?
Show Hint
Three options are real transport machinery; one is a lab reagent term.
Updated On: Jun 24, 2026
- Caveolins
- Local signals
- Importins
- Rat proteins
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: This is an "odd one out" item, so the strategy is to confirm three genuine players in nuclear traffic and let the fourth stand out as the answer.
Step 2: Importins clearly qualify. They are a class of karyopherin that grab a cargo's nuclear localisation sequence and ferry it through the nuclear pore, using importin $\alpha$ and $\beta$ subunits.
Step 3: Local signals also qualify, since the localisation and export sequences on cargo proteins are what tell the transport machinery where to send them. Caveolins are membrane scaffolding proteins that have been linked to shuttling and signalling, so they too can be tied to transport.
Step 4: That leaves rat proteins, which is simply recombinant material used in laboratory cell culture and has nothing to do with nucleocytoplasmic transport, so it is the exception.
\[\boxed{\text{Rat proteins}}\]
Step 2: Importins clearly qualify. They are a class of karyopherin that grab a cargo's nuclear localisation sequence and ferry it through the nuclear pore, using importin $\alpha$ and $\beta$ subunits.
Step 3: Local signals also qualify, since the localisation and export sequences on cargo proteins are what tell the transport machinery where to send them. Caveolins are membrane scaffolding proteins that have been linked to shuttling and signalling, so they too can be tied to transport.
Step 4: That leaves rat proteins, which is simply recombinant material used in laboratory cell culture and has nothing to do with nucleocytoplasmic transport, so it is the exception.
\[\boxed{\text{Rat proteins}}\]
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