UAA and UAG may Encode Amino Acid in Cathepsin B Gene of Euplotes octocarinatus
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Updated: Jan 20, 2026

Optical Control of a Neuronal Protein Using a Genetically Encoded Unnatural Amino Acid in Neurons
Published on: March 28, 2016
Ruanlin Wang1, Jingni Liu1, Graziano Di Giuseppe2
1Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, China.
Abstract:
The ciliate Euplotes deviates from the universal genetic code by translating UGA as cysteine and using UAA and UAG as the termination codon. Here, we cloned and sequenced the Cathepsin B gene of Euplotes octocarinatus (Eo-CTSB) which containing several in-frame stop codons throughout the coding sequence. We provide evidences, based on 3'-RACE method and Western blot, that the Eo-CTSB gene is actively expressed. Comparison of the derived amino acid sequence with the homologs in other eukaryotes revealed that UAA and UAG may code for glutamine in Eo-CTSB. These findings imply an evolutionary complexity of stop codon reassignment in eukaryotes.
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