Crystallin gene expression during rat lens development.
The analysis of the developmental pattern of the alpha A-, alpha B-, beta B1-, beta B2-, beta B3-, beta A3/A1-, and beta s-crystallin genes during fetal and postnatal development of the rat shows that the differential regulation of crystallin synthesis relies on differential gene shutdown rather than differential gene activation; that is, all crystallin genes are active during early development but turn off at different stages. The only two exceptions to this rule are the alpha B- and beta s-crystallin genes. The alpha B-crystallin gene transcript becomes first detectable at 18 days of fetal development, while the beta s-crystallin gene appears to be active only in the postnatal period. We also determined the absolute numbers of the alpha A-, alpha B-, beta B1-, beta B2-, beta B3-, beta A3/A1-, beta s-, and gamma-crystallin gene transcripts present in the lens at various times after birth. Comparison of these RNA data with the published protein data shows that the alpha B- and beta B2-crystallin RNAs are relatively overrepresented, suggesting the possibility that these two RNA species are not used as efficiently as other crystallin mRNAs. Examination of the known (hamster) alpha B-crystallin sequence and elucidation of the (rat) beta B2-crystallin sequence yielded no evidence for aberrant codon usage. These two RNAs have one sequence motif in common: they are the only crystallin mRNAs in which the translation initiation codon is preceded by CCACC.
Aarts
H J
HJ
Laboratory of Molecular Biology, University of Nijmegen.
Lubsen
N H
NH
Schoenmakers
J G
JG
D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003459:Crystallins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D004247:DNA / Q000032:analysis*; D007908:Lens, Crystalline / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D003459:Crystallins; D012333:RNA, Messenger; D004247:DNA