UPF3B（UPF3B regulator of nonsense mediated mRNA decay），癌症关联基因，基因ID：65109，该基因编码一种蛋白质，是参与mRNA核输出和mRNA监测的剪接后多蛋白复合物的一部分该编码蛋白是酵母upf3p的两个功能同源物之一，mrna监测检测具有截短开放阅读框的输出mrna，并启动无义介导的mrna衰变（nmd）。当翻译从最后一个外显子-外显子连接处上游结束时，这会触发NMD降解含有过早终止密码子的mrna该蛋白与mrna结合，在核输出后仍保持结合状态，充当核质穿梭蛋白。它与Y14形成一个复合物，在外显子-外显子连接上游特异结合20nt该基因位于x染色体的长臂上，发现了两个不同亚型的剪接变体。[由RefSeq提供，2008年7月]This gene encodes a protein that is part of a post-splicing multiprotein complex involved in both mRNA nuclear export and mRNA surveillance. The encoded protein is one of two functional homologs to yeast Upf3p. mRNA surveillance detects exported mRNAs with truncated open reading frames and initiates nonsense-mediated mRNA decay (NMD). When translation ends upstream from the last exon-exon junction， this triggers NMD to degrade mRNAs containing premature stop codons. This protein binds to the mRNA and remains bound after nuclear export， acting as a nucleocytoplasmic shuttling protein. It forms with。