The absence of the long 3'‐non‐translated region in mRNA coding for eye lens αA2‐crystallin of the frog (Rana temporaria)

Abstract

The nucleotide sequence of a cloned cDNA (clone pRt(1)297; GENE (1982) 17, 131) coding for a 18 kDa polypeptide of the frog eye lens has been determined. The sequence, 791 nucleotide in length has only one long open reading frame (447 nucleotides). The derived amino acid sequence in this frame has > 90% homology with the region 25–173 of αA2-crystallin amino acid sequence from a related frog species Rana pipiens. The 5'-terminal part of mRNA corresponding to the first 24 amino acids of αA2-crystallin has been lost in cloning and substituted by an artefactual sequence. The 3'-terminal part appears to be intact as follows from the presence of the universal poly(A) addition site and poly(A) tract. The 3'-nontranslated region present in frog αA2-crystallin mRNA (130 nucleotides) is about 4-times shorter than in mammalian αA2-crystallin mRNA. Intact αA2-crystallin mRNA with a size of about 700 nucleotides as determined by Northern blot hybridization is about twice smaller than corresponding mammalian mRNAs