Microheterogeneity at the <i>C</i>-terminus of γ-crystallin fraction IVb

Slingsby, C.; Croft, L. R.

doi:10.1042/bj1270609

Cited by 12 publications

(4 citation statements)

References 9 publications

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“…However, as discussed below, >50% of the nucleotide changes do not alter the encoded amino acid, indicating strong selection pressure for a large number of the residues in the y-crystallin polypeptides. These observations are consistent with earlier protein studies that indicated that y-crystallins vary more at the COOH-terminal than at the NH2-terminal end (6,20,21).…”

Section: Results and Commentssupporting

confidence: 82%

Gamma-crystallin family of the mouse lens: structural and evolutionary relationships.

Breitman¹,

Lok²,

Wistow³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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The heterogeneity inherent among r-crystallins of the mouse lens was investigated by sequence analysis of three r-crystallin-specific cDNAs. Comparison of the nucleotide sequence of these cDNAs and one previously reported by us revealed that the four r-cDNAs share 80-90% homology in nucleotide sequence. The entire 3' half of the coding region shows more variability than the 5' half, whereas the greatest variability is observed in the 3' untranslated region where numerous base substitutions, deletions, and insertions seem to have occurred. Alignment of the amino acid sequences of the four mouse y-crystallins according to the known four structural motifs of the major calf y-crystallin, y-II, suggests that all four mouse polypeptides are structurally very similar to calf y-II. However, most of the mouse polypeptides differ from v-II by the absence of one amino acid residue, resulting in a shorter connecting peptide between the two globular domains of the protein. Primary sequence alignment also revealed that the four mouse y-crystallins are most divergent in the third structural motif of the polypeptide. The significance of these differences in terms of the structure and function of the y-crystallins in the mouse lens is discussed.Approximately 90% of the soluble protein of the vertebrate lens consists of a group of structural proteins known as the crystallins (1, 2). In mammals, these lens-specific proteins can be divided into three antigenically distinct classes, a, 3,B and y, each of which comprises several polypeptides of related primary structure. The importance of the structure and function of these polypeptides has long been indicated by the tight developmental regulation of the different crystallin classes and by their differential spatial distribution within the lens (3).At present, little is known about the functional significance of the heterogeneity inherent among the polypeptides of each crystallin class. As a first step towards addressing this question, we have been involved in a study of the structure of the y-crystallins of the mouse. In the mouse lens, up to seven different y-crystallin polypeptides can be identified by two-dimensional gel electrophoresis (4) and a similar number has been reported for several other animal species (5-7). A number of y-crystallin-specific cDNAs have been isolated from a variety of animal species (5, 8-11) and these have been analyzed by DNA sequencing. We (12) and others (13,14) have shown that the y-crystallins of representative gene members of mice and rats are encoded by a family of genes with a similar structure. All of them contain a small 5' exon, encoding three amino acids, followed by two larger exons of approximately equal size that encode the remainder of the "20-kilodalton polypeptide (12-14). There is a precise correspondence between the two major exons of the gene and the two similar structural domains of the polypeptide, suggesting that the y-crystallins may have evolved by exon duplication and subsequent gene amplification (12)(13)(14).The nucl...

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Section: Results and Commentssupporting

confidence: 82%

Gamma-crystallin family of the mouse lens: structural and evolutionary relationships.

Breitman¹,

Lok²,

Wistow³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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“…The presence of the Alu I-like sequences at the end of the 3' coding region may explain the origin of the heterogeneity of the carboxy-terminal region, e.g., the carboxy-terminal tetrapeptide (Slingsby and Croft, 1972). The stem of the hairpin shown in Fig.…”

Section: G-t-g-a-t-g-g-mentioning

confidence: 98%

Complete Nucleotide Sequence of a cDNA Derived from Calf Lens γ-Crystallin mRNA: Presence of Alu I-Like DNA Sequences

Bhat¹,

Spector²

1984

DNA

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The nucleotide sequence of a cloned cDNA derived from gamma-crystallin mRNA of calf lens was determined. The cloned cDNA contains the entire coding region 522 bp long, 30 nucleotides of the 5' noncoding region, and 67 residues in the 3' noncoding region followed by a poly(A) tail of 25 nucleotides. The deduced amino acid sequence directly demonstrates for the first time that the calf gamma-crystallin contains 174 residues. The nucleotide sequence contains a number of interesting features including a 32-bp sequence in the 3' region with 70% complementarity to the 3' end of the first monomer unit of the consensus Alu I DNA. Within this region, a 32-bp sequence shows about 80% homology with a segment of hamster 4.5S RNA. The possible evolutionary and regulatory significance of these sequences is discussed.

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“…In view of the similarity ofthe primary structures ofthe y-crystallin polypeptides (8)(9)(10)12), it is possible that differences in the putative 3' untranslated region of the mDNAs contribute to the ability of the mouse ycrystallin cDNA clones to select their complementary mRNA under stringent conditions for mRNA-cDNA hybridization. Differences in the 3' translated region of the y-crystallin mRNAs (included in our clones) must also be present since studies on the bovine (28,29) and haddock (30) lens have shown that there is heterogeneity at the COOH termini of the y-crystallin polypeptides. Moreover, amino acid sequence data on bovine lens ycrystallins reveal that there are also differences throughout these polypeptide chains (12).…”

Section: Discussionmentioning

confidence: 99%

Multiple gamma-crystallins of the mouse lens: fractionation of mRNAs by cDNA cloning.

Shinohara¹,

Robinson²,

Appella³

et al. 1982

Proc. Natl. Acad. Sci. U.S.A.

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cDNAs made from polyadenylylated RNAs ofthe mouse lens were cloned by the G-C tailing procedure in the bacterial plasmid pBR322. Four recombinant DNAs containing vcrystallin sequences were identified by hybrid selection and translation. Sequence analysis of the in vivo-labeled y-crystallin polypeptides that cofocused isoelectrically with the hybrid-selected translation products established that the four cloned cDNAs were derived from mRNAs encoding y-crystallin polypeptides with similar NH2 termini. The cDNA clones had different restriction maps and could discriminate among the different y-crystallin mRNAs under stringent hybridization conditions. Under relaxed hybridization conditions, the cDNA clones cross-hybridized with all ycrystallin mRNAs, and even slightly with 13-crystallin mRNAs, as judged by in vitro translation. RNA blot hybridization showed that the mouse lens y-crystallin mRNAs are 840 ± 100 nucleotides long. These data indicate that there are at least four similar ycrystallin mRNAs and suggest (but do not establish) the existence of a closely related family of y-crystallin genes.The crystallins are a group of structural proteins that constitute 90% ofthe soluble protein ofthe vertebrate lens (1, 2). There are four immunologically distinct classes of crystallins called a-, 1,-, y-, and 8-crystallin. The mammalian lens lacks 8-crystallin, which is confined to birds and reptiles (3, 4). Each crystallin class is composed of a family of polypeptides that have related primary structures. The crystallin polypeptides are highly conserved evolutionarily (5) and are differentially synthesized during lens development (6).The existence of multiple related polypeptides in each crystallin class has made it difficult to know which polypeptide is a primary gene product and which is posttranslationally derived from a precursor polypeptide. Numerous posttranslational changes, such as deamidation, cleavage, and oxidation, occur among the crystallins during maturation and aging of the lens (for review, see refs. 1, 2, and 7). One obvious approach to understanding the basis for the multiplicity of the crystallin polypeptides is to identify and fractionate their various mRNAs. This is most efficiently carried out by cloning the crystallin cDNAs. The identified crystallin cDNA clones can then be used for investigations on the crystallin genes.This study concerns the y-crystallins. These are the smallest ofthe crystallin polypeptides (Mr 18,000-20,000) and have similar immunological and structural properties (1,5,(8)(9)(10). Protein sequence data indicate that there are at least three different genes for y-crystallins in the bovine lens (11, 12). Here we show by analysis of cDNA clones and amino acid sequence data that four major y-crystallin polypeptides of the 5-to 10-day-old mouse lens have similar but different mRNAs. MATERIALS AND METHODSMaterials. Avian myeloblastosis virus RNA-dependent DNA nucleotidyltransferase (reverse transcriptase) was obtained from J. W. Beard. Escherichia coli DNA polymerase I and ...

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Microheterogeneity at the C-terminus of γ-crystallin fraction IVb

Cited by 12 publications

References 9 publications

Gamma-crystallin family of the mouse lens: structural and evolutionary relationships.

Gamma-crystallin family of the mouse lens: structural and evolutionary relationships.

Complete Nucleotide Sequence of a cDNA Derived from Calf Lens γ-Crystallin mRNA: Presence of Alu I-Like DNA Sequences

Multiple gamma-crystallins of the mouse lens: fractionation of mRNAs by cDNA cloning.

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