Data from: Peroxisomal lactate dehydrogenase is generated by basal translational readthrough in mammals

Translational readthrough gives rise to low abundance proteins with
C-terminal extensions beyond the stop codon. To identify functional
translational readthrough, we estimated the readthrough propensity (RTP)
of all stop codon contexts of the human genome by a new regression model
in silico, identified a nucleotide consensus motif for high RTP by using
this model, and analyzed all readthrough extensions in silico with a new
predictor for peroxisomal targeting signal type 1 (PTS1). Lactate
dehydrogenase B (LDHB) showed the highest combined RTP and PTS1
probability. Experimentally we show that at least 1.6% of the total
cellular LDHB getting targeted to the peroxisome by a conserved hidden
PTS1. The readthrough-extended lactate dehydrogenase subunit LDHBx can
also co-import LDHA, the other LDH subunit into peroxisomes. Peroxisomal
LDH is conserved in mammals and likely contributes to redox equivalent
regeneration in peroxisomes.

翻译通读（translational readthrough）可产生在终止密码子下游带有C端延伸序列的低丰度蛋白质。为鉴定具有功能的翻译通读事件，本研究借助全新的计算机回归模型，对人类基因组中所有终止密码子上下文的通读倾向度（readthrough propensity, RTP）进行了估算；通过该模型，我们还鉴定出了与高RTP相关的核苷酸共有基序；同时利用一款全新的过氧化物酶体靶向信号1型（PTS1）预测工具，对所有通读延伸序列开展了in silico分析。乳酸脱氢酶B（LDHB）的RTP与PTS1预测概率综合得分最高。本研究通过实验证实，细胞内至少1.6%的总LDHB可通过一段保守的隐蔽PTS1被靶向转运至过氧化物酶体。经翻译通读延伸得到的乳酸脱氢酶亚基LDHBx，还可将另一种乳酸脱氢酶亚基LDHA共转运至过氧化物酶体中。过氧化物酶体定位的乳酸脱氢酶在哺乳动物中具有进化保守性，其可能参与过氧化物酶体内的氧化还原当量再生过程。