Vertebrate and invertebrate crystallin genes have been investigated. Comparison of the 5'- flanking sequences of the chicken, mouse, and human alphaA-crystallin gene suggests a modular arrangement of control motifs, whose locations and orientations are species dependent. Upstream repetitive elements in the alphaA gene of each species suggest interesting structural or control functions. The alphaA-CRYBP1 site is generally conserved, but transfection experiments indicate that it may be more important in the mouse than the chicken gene. Site-directed mutagenesis, gel retardation, and footprinting experiments indicate that numerous control elements are operative in the mouse and chicken alphaA promoter. An upstream promoter was identified in the multifunctional alphaB-crystallin gene used in lung and other tissues; a lens and muscle enhancer found between the two alphaB promoters was shown to contain a protein-binding site just upstream of an AP-2-like sequence. Minimal functional promoters were identified in the chicken betaB1- and betaA3/A1-crystallin genes in transfection experiments and are being tested in transgenic mice. The duck delta2-crystallin cDNA was shown to encode acive argininosuccinate lyase by transformation into yeast and expression in bacteria. The major octopus and squid crystallins (S-crystallins) were definitively shown to be related to glutathione S-transferase (GST), but often have an extra unique internal peptide. Nine to ten squid S-crystallin genes were identified by hybridization; two were characterized in detail and shown to be similar to mammalian GST genes. Minimal functional S-crystallin promoters were identified in transfected chicken and rabbit lens cells. A minor aldehyde dehydrogenase-like crystallin was found in octopus, providing the first common enzyme-crystallin for vertebrates and invertebrates. Three very similar, intronless, active jellyfish crystallin genes have been cloned and sequenced. Their cDNA's have poly A tails but no recognizable polyadenylation signal.
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