ISSN:
1573-4978
Keywords:
β-crystallin
;
leaky ribosomal scanning
;
translation initiation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Leaky ribosomal scanning allows the expression of multiple proteins from a single mRNA by occasionally skipping the first start codon, and initiating translation at a subsequent one. βA3- and βA1-crystallin, two members of the β-crystallin family of vertebrate eye lens proteins, are produced via this mechanism, of which, until now, only very few examples have been found in eukaryotic genes. Since the two start codons on the βA3/A1 messenger lie in the same reading frame, the two translated proteins are identical, except for the 17 residues shorter N-terminal extension of βA1-crystallin. It has been suggested that the very short leader (5–7 nucleotides) of the βA3/A1 messenger might cause slippage at the first start codon, although the unfavorable context of this start codon might also be responsible. Using transient transfections, we now demonstrate that increasing the length of the leader sequence to 67 nucleotides indeed completely abolishes translation initiation at the second start codon, and thus expression of the βA1-crystallin protein. Messengers having a leader of 5, 7 or 14 nucleotides all express both βA3- and βA1-crystallin at very similar relative levels.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007046926233
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