Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human cataractous lenses from subjects aged 20-91 years were extracted in tris/glycine buffer and fractionated on Sephadex G-75 column. Four fractions, F1, F2, F3 and F4 identified as alpha-, beta1-, beta2- and gamma-crystallin were obtained. Gel electrophoresis of alpha-crystallin in polyacrylamide containing 6M urea revealed changes in polypeptide composition, colouration; variation in band pattern and mean mobility. The relative mobilities of the protein bands were used to calculate coefficient of similarity within the same age group and among different age groups.
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PMID:Variations in the soluble alpha-crystallin proteins from human cataractous lenses. 9 55

The A2 and B2 polypeptide chains of calf lens alpha-crystallin are synthesized on a 14S, 1500-nucleotide mRNA and a 10S, 735-nucleotide mRNA, respectively. The 10S mRNA is theoretically compatible with the size of the B2 chain, but the 14S mRNA contains approximately twice the required number of nucleotides necessary for A2 chain synthesis. This fact raises the question of the function of the additional nucleotide sequence in the 14S mRNA. The following observations on 14S mRNA suggest that it may contain an additional cistron. (i) Under a number of denaturing conditions, 14S mRNA continues to retain its initial size characteristics. (ii) In addition to synthesis of the A2 chain, 14S mRNA directs the synthesis of another polypeptide with the same electrophoretic mobility as that of the B2 chain. (iii) Molecular hybridization of the 14S mRNA with the cDNA produced from the 10S mRNA suggests that 2 mol of the cDNA bind to 1 mol of the 14S mRNA. (iv) Examination of the nucleotide sequences of the 10S and 14S mRNAs by two-dimensional maps of RNase A and T1 digests indicates marked similarity. The overall data suggest that the additional cistronic component may carry coding information for an alpha-crystallin polypeptide or a closely related polypeptide species.
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PMID:The bicistronic nature of lens alpha-crystallin 14S mRNA. 27 67

Total poly(A)-containing calf lens mRNA was microinjected into Xenopus oocytes and synthesis of alpha, beta, and gamma-crystallins was demonstrated. By a method of quantitative immunoprecipitation the rate of translation of purified 14S alphaA2-crystallin mRNA was compared with translation of 9-S rabbit globin mRNA. Maximal response of oocytes was obtained with virtually the same molar amounts of mRNA, taking into account the larger size of the alphaA2-crystallin mRNA. Kinetics of translation were also very similar and both mRNAs were translated with similar rate and efficiency for at least two days. It was estimated that 20-30 polypeptide chains per hour per mRNA molecule were synthesized.
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PMID:Synthesis of lens crystallins in Xenopus oocytes as determined by quantitative immunoprecipitation. 35 34

In this paper evidence is provided that one of the protein components of the water-soluble fraction of the calf lens binds specifically to deoxyribonuclease I (DNAse I). On the basis of this property, the polypeptide could be purified by applying DNAse I affinity chromatography. Concomitantly a protein of Mr55000 and a rather large amount of alpha-crystallin copurify with this polypeptide, which has a molecular weight of 42000. Highly purified 42000-Mr protein was also obtained by extraction of the water-insoluble fraction of the calf lens with 2-([tris(hydroxymethyl)methyl]amino) ethanesulfonic acid followed by gel filtration. Amino acid analyses, peptide mapping and electron microscopy show that the protein obtained from both lens fractions is identical to non-muscle actin. Furthermore the amino acid composition of the 55000-Mr protein is identical to hog stomach skeletin and very similar to calf brain desmin.
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PMID:Actin in mammalian lens. 44 81

The soluble proteins from bovine lens homogenate were separated on Sepharose CL-6B (2 X 200 cm) in 0.05 M tris-NaHSO3 pH 8.2 buffer containing 20 mM EDTA. Five sharp and defined fractions (HM alpha, alpha, beta H, beta L, gamma) were obtained. Each crystallin fraction was further purified by rechromatography on the same column. Each protein fraction was pure as judged by ultracentrifugation and SDS-gel electrophoresis. The molecular weights of the five fractions were 3.04 x 10(6), 5.83 x 10(5), 1.58 x 10(5) , 4.59 x 10(4), 2.14 x 10(4) as determined from sedimentation coefficient and intrinsic viscosity data by Scheraga-Mandelkern equation, which was in close agreement with that obtained by gel filtration. The polypeptide composition of crystallins as determined by SDS-gel electrophoresis revealed one band for high molecular weight alpha (HM alpha) and alpha, three for beta H, two for beta L and one for gamma. The gross CD patterns of crystallins were about the same in the peptide region (200 nm similar to or approximately 250 nm) with a minimum centered at about 217 nm, indicative of a beta-sheet structure in all crystallins. The [theta] values at 217 nm ranged from --1700 to --3700 degrees cm2 per decimole. The CD spectra of these crystallins in the aromatic region (250 nm similar to or approximately 300 nm) were different, reflecting the different contributions of aromatic amino acids to the tertiary structure of crystallins.
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PMID:Isolation and physical characterization of bovine lens crystallins. 45 34

A method has been developed to isolate and characterize beta-crystallins of rabbit lens cortex. Chromatographic separation of water-soluble structure proteins of rabbit lens cortex on a Sephacryl S-200 gel column yielded four beta-crystallin peaks (beta1, beta2, beta3 and beta4), all eluting between alpha and gamma-crystallins. Their molecular weights were estimated to be 250,000, 130,000, 60,000, and 37,000 daltons, respectively. SDS-gradient gel electrophoresis of these beta-crystallins gave rise to characteristic polypeptides; beta1, two polypeptides of 30,000 and 23,000 daltons; beta2, one major polypeptide of 33,000; beta3; two polypeptides of 28,000 and 26,000; and beta4, two polypeptides of 22,500 and 11,200 daltons. From a knowledge of the molecular weights and the ratio of the polypeptides in each crystallin, their oligomeric structure was calculated to be 5:5, 4, 1:1, and 1:1. The relative abundance of these four beta-crystallins was found to be 25.6%, 7.2%, 27.2%, and 2.8% of the total water-soluble proteins of the lens cortex.
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PMID:Studies on lens proteins. I. Subunit structure of beta crystallins of rabbit lens cortex. 66 95

14-S mRNA from rat lens codes for two subunits of alpha-crystallin, A2 (Mr 20 000) and AIns (Mr 24 000, previously referred to as alphaX). Structural relationship between both translation products has been proved by immunoprecipitation with antisera directed against the different crystallin classes. Competition immunoprecipitation showed that the 14-S mRNA translation products are precipitated by common antibodies, specific for the A subunit of alpha-crystallin. Two-dimensional gel electrophoresis and peptide analysis provided further evidence that the 24 000-Mr polypeptide, synthesized in vitro under direction of 14-S mRNA, is identical with native alphaAIns. Although the structures of alphaA2 and alphaAIns are very similar, no precursor-product relationship exists between both 14-S-mRNA-encoded polypeptides.
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PMID:Two structurally closely related polypeptides encoded by 14-S mRNA isolated from rat lens. 69 10

The major beta-crystallin fractions from the human lens and the lenses of other selected primates have been isolated and partially characterized. Primate beta-crystallins, like those of most other mammals, consist of two heterogenous protein fractions (betaH and beta L) of quite different molecular size. Most of the polypeptide chains comprising the betaH and beta L heteropolymers are common to both fractions. Evidence is presented suggesting that primate betaH-crystallin may be smaller than betaH from other vertebrate species. Additionally, human betaH is found to contain a major component on sodium dodecyl sulfate (SDS) electrophoresis which is much larger (about 60,000 daltons) than other beta-crystallin polypeptides. Immunochemical evidence inidcates that some components of primate beta-crystallin have evolved rapidly, although at least one antigenic component is very conservative and gives a reaction of identity with all other vertebrate beta-crystallins studied.
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PMID:Studies on beta-crystallin from primate lens. 82 96

Upon addition of lens polyribosomes to a reticulocyte-cell-free system, alpha, beta L-, and gamma crystallin are synthesized, while beta H crystallin is not formed. This phenomenon is comparable to the biosynthetic events in the lens-cell-free system and in tissue culture. It is shown that beta H crystallin formation depends upon the presence of a polypeptide beta B1 b which arises by posttranslational modification. The putative precursor for beta B1 b is a polypeptide beta BU a of which the messenger with a sedimentation coefficient of 12.5 S has been isolated.
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PMID:Synthesis of lens protein in vitro: formation of beta-crystallin. 91 13

The specificity of a dialyzable component, isolated from rabbit reticulocyte initiation factors, in stimulating protein synthesis was examined. It appeard that his factor (hereafter designated as "iRNA") was able to restore the activity of initiation factor preparations that were inactivated by dialysis. The "iRNA" from reticulocytes stimulated polypeptide synthesis directed by the homologous globin mRNA as well as heterologous lens crystallin mRNAs. No selectivity in its stimulating action with regard to the type of mRNA studied could be observed. The source of ribosomes or supernatant enzymes did not influence the effect of "iRNA". However, in an ascites lysate that was dependent on the addition of initiation factors, "iRNA" increased polypeptide formation only marginally, suggesting that in this lysate a similar factor was already present in an active form. It is concluded that "iRNA" may regulate protein synthesis, but without exhibiting specificity towards mRNAs, at least those tested so far.
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PMID:Non-specific stimulation of cell-free protein synthesis by a dialyzable factor isolated from reticulocyte initiation factors ("iRNA"). 105 49


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