Human choline acetyltransferase mRNAs with different 5′-region produce a 69-kDa major translation product

Hidemi Misawa, Junko Matsuura, Yoshio Oda, Ryosuke Takahashi, Takeo Deguchi

研究成果: Article査読

54 被引用数 (Scopus)

抄録

Choline acetyltransferase (ChAT, EC 2.3.1.6) is the biosynthetic enzyme for acetylcholine. We have previously shown that multiple ChAT mRNA species with different 5′-noncoding regions are expressed in the rat and mouse. However, the diversity of ChAT mRNA species in human has not completely been elucidated. In this work N1- and N2-type ChAT cDNAs were cloned from a human brain cDNA library and the N-exon located in the human ChAT gene. Polymerase chain reaction analysis indicates that four species of ChAT mRNAs (R-, N1-, N2- and M-types) are produced in human brain and spinal cord. In all human transcripts, the ATG initiation codon in the rat, mouse and pig was replaced by ACG, which does not serve as an initiation codon for translation. In vitro translation and mammalian expression analyses revealed that N1-, N2- and R-type mRNAs give rise to a single 69 kDa enzyme, while M-type mRNA produces both 82 and 69 kDa enzymes. The translation efficiency of M-type mRNA was lower than that of the other mRNA species. Moreover, the translation efficiency of human ChAT mRNAs was considerably lower than that of rat ChAT mRNA, suggesting that the ATG codons for human ChAT are unfavorable for translation initiation compared with the initiation codon for rat ChAT. These results provide rational explanations for the previous reports that human ChAT protein purified from the brain and placenta had 66-70 kDa molecular mass, and that ChAT activity in a single motor neuron of human was far lower than that of other vertebrates. Sequencing of monkey ChAT gene showed that the initiation ATG in rodent ChAT was also replaced by ACA in the monkey.

本文言語English
ページ(範囲)323-333
ページ数11
ジャーナルMolecular Brain Research
44
2
DOI
出版ステータスPublished - 1997
外部発表はい

ASJC Scopus subject areas

  • 分子生物学
  • 細胞および分子神経科学

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