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

The ultrastructure and major soluble proteins of the transparent eye lens of two cubomedusan jellyfish, Tripedalia cystophora and Carybdea marsupialis, have been examined. Each species has two complex eyes (one large and one small) on four sensory structures called rhopalia. The lenses consist of closely spaced cells with few organelles. The lens is situated next to the retina, with only an acellular layer separating it from the photoreceptors. SDS-PAGE showed that the large lens of C. marsupialis has only two crystallin polypeptide bands (with molecular masses of approximately 20,000 and 35,000 daltons), while that of T. cystophora has three bands (two with a molecular mass near 20,000 daltons and one with a molecular mass near 35,000 daltons). Interestingly, the small lens of T. cystophora appears to be markedly deficient in or lack the lower molecular weight proteins. The crystallins behaved as monomeric proteins by FPLC and showed no immunological reaction with antisera of the major squid crystallin, chicken delta-crystallin or mouse gamma-crystallin in western immunoblots. Very weak reactions were found with antimouse alpha- and beta-crystallin sera. The 35,000 dalton crystallin of T. cystophora was purified and called J1-crystallin. It contained relatively high leucine (13%) and tyrosine (9%) and low methionine (2%). Several tryptic peptides were sequenced. Weak sequence similarities were found with alpha- and beta-crystallins, which may account for some of the apparent weak immunological cross-reactivity with these vertebrate crystallins. A polyclonal antiserum made in rabbits from a synthetic peptide of J1-crystallin reacted strongly with J1-crystallin of T. cystophora and C. marsupialis in immunoblots; by contrast, no reaction was obtained with the lower molecular weight crystallins from these jellyfish, with the squid crystallin, or with any crystallins from the frog or human lens. Thus, despite the structural similarities between the cubomedusan, squid and vertebrate lenses, their crystallins appear very different.
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PMID:The cellular eye lens and crystallins of cubomedusan jellyfish. 256 98

Lens crystallins isolated from the tadpole and frog lenses were compared with regard to the developmental changes of crystallin compositions. The major changes during the process of metamorphosis were (1) the total contents of alpha- and gamma-crystallins decrease from more than 70% to less than 60% and (2) one of the major beta-crystallin polypeptides increases from less than 1% to about 6% and (3) an amphibian-specific rho-crystallin also increases from about 6% to more than 10% of total soluble proteins of the lens. We have characterized the metamorphosis-dependent beta-crystallin polypeptide by peptide mapping and sequence determination of the protease-digested fragments. This polypeptide showed very high sequence homology to that of the major beta Bp-crystallin chain reported for the mammalian lenses. The changes of the relative abundance of various crystallins and the gradually-elevated levels of the expression of this beta Bp-like crystallin in the developing lens during metamorphosis may also have some bearing on the maintenance of lens stability in the adult frog lenses.
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PMID:Lens crystallin changes associated with amphibian metamorphosis: involvement of a beta-crystallin polypeptide. 259 Feb 9

Lenses from rat or calf were exposed in vitro to UV radiation from a nitrogen laser operated at 337.1 nm or from an excimer laser operated at 3.8 nm. Visible light transmission was monitored during calf lens irradiations at 308 nm and found to decrease. Proteins were extracted from the irradiated rat or calf lenses, separated into water soluble and insoluble fractions, and analysed using SDS-PAGE. Comparison of these gels with dark controls showed that, following photolysis, there was loss of polypeptide material in the 20-30 kDa region and concomitant formation of polymers at 40 and 60 kDa, and at greater than 100 kDa in calf lens (308 nm irradiation) and rat lenses (337.1 nm irradiation) in vitro. In addition, there was evidence for formation of lower molecular weight polypeptides at 10 kDa in the protein from irradiated rat lenses. The rat SDS-PAGE gels were challenged against anti-calf gamma crystallin serum. There was clear evidence that the polymeric material, in the water insoluble protein fraction from the 337.1 nm photolyzed rat lenses was derived in part from gamma crystallin. The macromolecular changes detected in these photolyzed rat and calf lens proteins were similar to those previously reported to accompany aging in the human lens. Biochemical changes of the type observed in UV irradiated rat and calf lenses may be responsible for the loss of visible light transmission seen in calf lenses.
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PMID:UV laser photodamage to whole lenses. 261 89

The soluble proteins--or crystallins--that constitute the bulk of the cellular, transparent eye lens are encoded by a surprisingly diverse group of genes. Several crystallin genes generate further heterogeneity by producing more than one polypeptide, in which they use different mechanisms. Some crystallin genes are lens specific (e.g., alpha A and gamma), while others show only lens preference (alpha B and enzyme/crystallins); all the crystallin genes are temporally and spatially regulated in the developing lens. Transfection and transgenic mouse experiments, identifying DNA regulatory elements in the 5' flanking region and in one case (delta) in an intron, point to transcriptional control as the primary basis for the tissue- and differentiation-specific expression of crystallin genes. Crystallin promoters have been used to target foreign genes to the lens in transgenic and chimeric mice. Such gene transfer experiments have been used to create tumors and ablate specific cells in the lens. The identification of trans-acting factors responsible for crystallin gene expression has begun but is in its infancy. The many mechanisms leading to the diversity and precise regulation of crystallins show that the lens is, in addition to a favorable tissue for studying differential gene expression, a fascinating portrait of molecular evolution.
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PMID:Lens crystallins and their genes: diversity and tissue-specific expression. 265 57

[14C]-amino acids and [32P]-orthophosphate incorporation experiments were carried out in bovine lenses in culture to study the synthesis and phosphorylation of alpha-crystallin A and B polypeptides during differentiation of the lens fiber cells. Following culture, the [14C] or [32P]-labelled alpha-crystallin was isolated by gel filtration chromatography from four regions of the lens corresponding to: A) quiescent epithelial cells, B) dividing epithelial cells and early stages of elongation, C) young elongating fibers, and D) mature fibers from the superficial cortex. The incorporation of label into the alpha-crystallin primary gene products alpha A2 and alpha B2 and their respective phosphorylated forms alpha A1 and alpha B1 was determined by isoelectric focusing and radioautography. Different synthesis and phosphorylation patterns were observed in alpha A and alpha B polypeptides. Synthesis and phosphorylation of the alpha B chain occurs most actively in the epithelial cells, both processes decrease during differentiation and there is no net accumulation of the phosphorylated form alpha B1 in the mature fiber cell. In contrast to the B chain, the A chain synthesis, minimal in the epithelial cell, increases with differentiation. Most striking, the A chain phosphorylation, not detectable in the epithelial cells, increases with differentiation. In the mature fiber cell, the phosphorylated form alpha A1 accounts for one third of the A chain. These observations indicate that the two chains may have different functions. the synthesis and phosphorylation patterns of alpha A suggest a lens-specific function of this polypeptide in the fiber cell and in the terminal differentiation process.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential synthesis and phosphorylation of the alpha-crystallin A and B chains during bovine lens fiber cell differentiation. 271 99

The water-insoluble fraction from mature bovine lens was solubilized to the same extent either by extraction with 6.0 M urea, by sonication of the suspended proteins or by a brief adjustment of the pH to 3.0 or 11.0. Sonication gave soluble protein levels of 50 mg ml-1 or greater with water or dilute buffers, but the presence of salt markedly diminished the solubility of the sonicated proteins. The sonicated proteins remained soluble upon storage at 5 degrees C, but were readily precipitated by either freezing or by the addition of salt. These re-precipitated proteins were once again insoluble when suspended in dilute aqueous buffers. Water-soluble alpha-crystallin at the same concentrations was unaffected by either high salt or freezing. The sonication-solubilized proteins were shown to be similar in aggregate size and polypeptide composition to the water-soluble HMW fraction isolated from the same lenses. An [125I]-labeled soluble HMW fraction was precipitated to the same extent as [125I]-labeled sonication-solubilized proteins upon freezing. The distribution of HMW aggregated protein between water-soluble aggregates and the water-insoluble fraction was unaltered by the presence of either dithiothreitol (DTT) or high levels of salt during the homogenization. The presence of either [125I]-labeled water-soluble HMW aggregates or [125I]-labeled water-insoluble sonicate supernatant during lens homogenization did not result in a significant incorporation of radioactivity into the water-insoluble fraction. These data argue that the water-insoluble fraction represents coalesced HMW aggregates which had already formed in the lens prior to homogenization. When the sonication-solubilized fraction was disaggregated in 6.0 M urea and then reaggregated by urea removal, the proteins no longer precipitated on freezing, and 85-90% of the protein eluted in the region of alpha-crystallin from an Agarose A-5m column. Only 3-6% of the original protein remained as a void volume peak, and was composed almost exclusively of highly crosslinked proteins. The limited solubility of the HMW proteins may therefore reflect the aggregate state of the alpha-crystallin rather than an inherent insolubility of the subunits.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Studies on the nature of the water-insoluble fraction from aged bovine lenses. 273 59

Cloned cDNA sequences specific for prostaglandin F (PGF) synthase have been isolated from a cDNA library of bovine lung mRNA sequences. Nucleotide-sequence analyses of cloned cDNA inserts have revealed that PGF synthase consists of a 969-base pair open reading frame coding for a 323-amino acid polypeptide with a Mr of 36,666. The sequence analysis indicates that bovine lung PGF synthase shows 62% identical plus conservative substitutions compared with human liver aldehyde reductase [Wermuth, B., Omar, A., Forster, A., Francesco, C., Wolf, M., Wartburg, J.P., Bullock, B. & Gabbay, K.H. (1987) in Enzymology and Molecular Biology of Carbonyl Metabolism: Aldehyde Dehydrogenase, Aldo-Keto Reductase, and Alcohol Dehydrogenase, eds. Weiner, H. & Flynn, T.G. (Liss, New York), pp. 297-307], which is similar to PGF synthase in molecular weight and substrate specificity. However, comparison of the amino acid sequence of PGF synthase with the National Biomedical Research Foundation protein data base reveals that the sequences of 225 amino acids from C termini of epsilon-crystallin of the European common frog (Rana temporaria) [Tomarev, S.I., Zinovieva, R.D., Dolgilevich, S.M., Luchin, S.V., Krayev, A.S., Skryabin, K.G. & Gause, G.G. (1984) FEBS Lett. 171, 297-302] and of PGF synthase show 77% identical and conservative substitutions without deletions/additions. The result suggests that European common frog lens epsilon-crystallin is identical to bovine lung PGF synthase.
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PMID:Structural similarity of bovine lung prostaglandin F synthase to lens epsilon-crystallin of the European common frog. 282 66

A post-translational protein modification system involving the polypeptide ubiquitin results in ubiquitin-protein conjugates of various functions. A ubiquitin-conjugating enzyme system was isolated from the epithelial tissue of bovine eye lens by DEAE-Sepharose and Bio-Gel A-1.5m column chromatography. The lens system shows similar enzymatic properties to the one from rabbit reticulocytes: requirement for ATP and sensitivity to thiol reagents. Two sets of prominent ubiquitin conjugates were formed with endogenous ubiquitin-acceptor proteins from fractions of the Bio-Gel column: a pair of ubiquitin conjugates of approximately 130 kDa and others with very high molecular mass. Extreme specificity is indicated by the ability of the lens system to catalyze conjugation of ubiquitin to the few endogenous acceptor proteins, or to histone H2B, but not to lysozyme, S-carboxymethylated bovine serum albumin, or native or heat-denatured lens alpha crystallin.
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PMID:Properties of the ubiquitin conjugation system from bovine eye lens. 284 35

alpha-Crystallin, a tissue specific structural protein of the ocular lens, is known to be composed of two subunits, alpha A and alpha B. By using a specific antibody in an immunoblotting procedure we have found that one of the subunits, alpha B is present in a number of non-lenticular tissues including the retina, heart, skeletal muscle, skin, brain, spinal cord and lungs. Interestingly, in the rat, this protein is present in significantly higher concentrations in adult than in fetal tissues and, with the exception of the lens, fetal and adult heart has the highest concentration among the tissues examined. That the protein in question is, in fact, alpha B, was confirmed a) by the remarkable similarity of Staphylococcus aureus protease peptide maps of the protein in the heart and purified alpha-crystallin and b) by the sequence analysis of a rat heart cDNA clone identified by the alpha B antibody. Based on these observations we conclude that while alpha A has a tissue-specific role, alpha B is a polypeptide of independent function not restricted to the ocular lens.
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PMID:alpha B subunit of lens-specific protein alpha-crystallin is present in other ocular and non-ocular tissues. 291 53

The life cycle transformation of the protozoan parasite Leishmania from promastigote to amastigote is accompanied by changes in the level of expression of a number of proteins whose function may be necessary for parasite survival in the sandfly vector or mammalian host. To genetically characterize these proteins, we have cloned and characterized cDNA sequences that vary in abundance during the life cycle of Leishmania major. One sequence (P100/11E) encodes a poly(A+) RNA whose abundance is markedly elevated in promastigotes of L. major. The DNA sequence of the P100/11E cDNA predicts an acidic polypeptide of Mr = 32,000 which shows 40-46% similarity to the superfamily of reductase proteins including 2,5-diketo-D-gluconic acid reductase, aldose reductase, aldehyde reductase, and rho-crystallin. The P100/11E sequence of L. major contains the IPKS motif located at the active site of both aldose and aldehyde reductases. The P100/11H sequence was expressed in Escherichia coli, and the purified polypeptide was used to raise rabbit antisera which detect a protein of Mr = 35,000 in promastigotes of L. major. These results provide direct genetic evidence that L. major expresses a sequence homologous to the reductase superfamily as a developmentally regulated gene product in promastigotes.
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PMID:The developmentally regulated P100/11E gene of Leishmania major shows homology to a superfamily of reductase genes. 291


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