ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThree-dimensional structure, catalytic properties, and evolution of a sigma class glutathione transferase from squid, a progenitor of the lens S-crystallins of cephalopodsXinhua Ji, Erik C. von Rosenvinge, William W. Johnson, Stanislav I. Tomarev, Joram Piatigorsky, Richard N. Armstrong, and Gary L. GillilandCite this: Biochemistry 1995, 34, 16, 5317–5328Publication Date (Print):April 25, 1995Publication History Published online1 May 2002Published inissue 25 April 1995https://pubs.acs.org/doi/10.1021/bi00016a003https://doi.org/10.1021/bi00016a003research-articleACS PublicationsRequest reuse permissionsArticle Views282Altmetric-Citations151LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (3)»Supporting Information Supporting Information Get e-Alerts
Abstract The nucleotide sequence of two cDNA clones corresponding to the beta B1-crystallin mRNA (formerly beta 35) of the chicken eye lens has been determined. The derived amino acid sequence of the chicken beta B1 polypeptide fits well with the two-domain, four Greek Key motif structure common to the beta gamma-crystallin superfamily of proteins. The calculated molecular weight of the encoded chicken beta B1 protein is 27,267. The beta B1 polypeptide has both an N- and C-terminal extension and is highly homologous to the mammalian beta B1-crystallin polypeptide. There is a 72% homology between the core regions of the chicken and bovine beta B1 polypeptides; by contrast, there is only 27% homology between the N-terminal extensions of these polypeptides. The N-terminal extension of chicken beta B1 contains a short alternating proline-alanine (PAPA) sequence, like that in the mammalian beta B1, and has some homology with the N-terminal region of histone H1.4, myosin light chain, prokaryotic outer membrane protein A, and adenovirus 24/28-kDa early protein. At the nucleic acid level, the chicken beta B1 crystallin gene has an atypical polyadenylation signal, AATTAAA. This appears to be associated with microheterogeneity of the polyadenylation site by comparison of two cDNA clones, suggesting an additional level at which diversity in crystallin gene expression may arise.
ABSTRACT In vivo corneal light scattering measurements using a novel confocal microscope demonstrated greatly increased backscatter from corneal stromal fibrocytes (keratocytes) in opaque compared to transparent corneal tissue in both humans and rabbits. Additionally, two water-soluble proteins, transketolase (TKT) and aldehyde dehydrogenase class 1 (ALDH1), isolated from rabbit keratocytes showed unexpectedly abundant expression (∼30% of the soluble protein) in transparent corneas and markedly reduced levels in opaque scleral fibroblasts or keratocytes from hazy, freeze injured regions of the cornea. Together these data suggest that the relatively high expressions of TKT and ALDH1 contribute to corneal transparency in the rabbit at the cellular level, reminiscent of enzymecrystallins in the lens. We also note that ALDH1 accumulates in the rabbit corneal epithelial cells, rather than ALDH3 as seen in other mammals, consistent with the taxon-specificity observed among lens enzyme-crystallins. Our results suggest that corneal cells, like lens cells, may preferentially express water-soluble proteins, often enzymes, for controlling their optical properties.
The murine alpha B-crystallin gene was cloned and its expression was examined. In the mouse, significant levels of alpha B-crystallin RNA were detected not only in lens but also in heart, skeletal muscle, kidney, and lung; low and trace levels were detected in brain and spleen, respectively. The RNA species in lung, brain, and spleen was 400 to 500 bases larger than that in the other tissues. Transcription in lens, heart, skeletal muscle, kidney, and brain initiated at the same position. A mouse alpha B-crystallin mini-gene was constructed and was introduced into the germ line of mice, and its expression was demonstrated to parallel that of the endogenous gene. Transgene RNA was always detected in lens, heart, and skeletal muscle, while expression in kidney and lung was variable; it remains uncertain whether there is transgene expression in brain and spleen. These results demonstrate that regulatory sequences controlling expression of the alpha B-crystallin gene lie between sequences 666 base pairs upstream of the transcription initiation site and 2.4 kilobase pairs downstream of the poly(A) addition site and are not located within the introns. Transfection studies with a series of alpha B-crystallin mini-gene deletion mutants revealed that sequences between positions -222 and -167 were required for efficient expression in primary embryonic chick lens cells; sequences downstream of the poly(A) addition signal were dispensable for expression in this in vitro system.
