| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 102 === Ribosomes biogenesis is a highly energy-consuming process in the cell. The synthesis starts from the nucleolus and matures in the cytoplasm, where ribosomes carry out protein translation. Ribosomes are very large complexes and cannot pass through the nuclear pore complex (NPC) on their own. In addition, the function of export receptors, including Mex67-Mtr2, Crm1and Arx1, is to help the ribosomal subunits out of the nucleus by assisting interaction between the ribosome and the NPC. Further, they also function as transacting factors and regulation points in ribosome biogenesis.
In this study, we found that C-terminal myc tag fusion Rlp24 (ribosomal-like protein 24) complemented the function of Rlp24 and did not show any negative effects in wild-type cells. However, it severely impaired the growth of the mutants with 60S export defects, including several nucleoporin mutants and other ribosome export mutants. In further examinations we found that none of these nucleoporins in NPC interact directly with Rlp24 yet show genetic interaction with RLP24. This suggests that these nucleoporins may participate in helping the release of Rlp24 by AAA-ATPase Drg1. On the other hand, if we overexpress Mex67 or Mtr2 in nup120Δ with Rlp24-myc, the dominant negative growth defects will be rescued. This result implicates possible interaction between Mex67-Mtr2 and Rlp24.
In addition, overexpression of Rlp24-myc caused other assembly factors such as Nog1, Mrt4 and Tif6 fail to be released from the pre-60S subunits and this defect was further enhanced when coupled with arx1Δ or nup120Δ, suggesting that the correct export process of pre-60S is important for the downstream maturation steps.
|
|---|
