Correct option is C
Explanation-
Statement A - RanGTP levels are higher in the nucleus than the cytoplasm - CORRECT
RanGTP is generated in the nucleus via RanGEF (RCC1), while RanGAP (which hydrolyzes RanGTP to RanGDP) is in the cytoplasm. This gradient drives the directionality of nuclear transport.
Statement B - Nuclear import receptors can shuttle between the nucleus and cytoplasm - CORRECT
Importins bind cargo in the cytoplasm, transport it into the nucleus, release the cargo upon RanGTP binding, and return to the cytoplasm.
Statement C - NTF2 transports RanGDP into the cytosol - INCORRECT
NTF2 actually transports RanGDP into the nucleus, not into the cytosol. Once in the nucleus, RanGDP is converted back to RanGTP by RCC1.
Statement D - Export of mRNA is not directly dependent on Ran - CORRECT
mRNA export is Ran-independent. It involves NXF1/TAP-p15 heterodimer rather than classical exportins.
Statement E - tRNA and miRNA export is mediated by exportins - CORRECT
Exportin-t exports tRNAs. Exportin-5 exports pre-miRNAs in a RanGTP-dependent manner.
Correct Answer: Option c (A, B, D, E only)
