A cytoskeletal protein unique to lens fiber cell differentiation

Ireland, Mark E.; Maisel, H.

doi:10.1016/0014-4835(84)90182-9

Cited by 100 publications

(73 citation statements)

References 11 publications

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“…The identity of the beads at that time was unknown, but these are now thought to be associated α-crystallin particles (34) ( Figure 3B). Through the 1980s, Maisel and his group pioneered the biochemical characterization of the chicken lens beaded filament fraction (35) and subsequently found beaded filaments in mammalian lenses as well (36). Morphologically similar structures immunologically related to mammalian beaded filament proteins were also identified in other chordate lenses (37), suggesting that the beaded filament is a structure that is fundamental to lens function in this phylum.…”

Section: Lenticular Beaded Filamentsmentioning

confidence: 99%

Functions of the intermediate filament cytoskeleton in the eye lens

Song¹,

Landsbury²,

Dahm³

et al. 2009

J. Clin. Invest.

160

107

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Intermediate filaments (IFs) are a key component of the cytoskeleton in virtually all vertebrate cells, including those of the lens of the eye. IFs help integrate individual cells into their respective tissues. This Review focuses on the lens-specific IF proteins beaded filament structural proteins 1 and 2 (BFSP1 and BFSP2) and their role in lens physiology and disease. Evidence generated in studies in both mice and humans suggests a critical role for these proteins and their filamentous polymers in establishing the optical properties of the eye lens and in maintaining its transparency. For instance, mutations in both BFSP1 and BFSP2 cause cataract in humans. We also explore the potential role of BFSP1 and BFSP2 in aging processes in the lens.

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Section: Lenticular Beaded Filamentsmentioning

confidence: 99%

Functions of the intermediate filament cytoskeleton in the eye lens

Song¹,

Landsbury²,

Dahm³

et al. 2009

J. Clin. Invest.

160

107

View full text Add to dashboard Cite

show abstract

“…Intermediate filament networks composed of vimentin are present in the lens epithelium and newly differentiated fiber cell, but disappear from older fiber cells (52,53). In a seemingly complementary manner, beaded filament proteins are not expressed in the epithelium and first emerge in the maturing fiber cell and then persist well into the lens (7,12,54). In those regions where the two networks coexist, they appear to be independent of one another.…”

Section: Resultsmentioning

confidence: 99%

“…Two proteins, CP49 (phakinin (10)) and CP115/CP95 (filensin (11)), have been localized to the beaded filament. Both proteins have been shown by Northern and Western blotting to be expressed only in the lens and only in the differentiated fiber cells of the lens (7,9,12,13). Also tightly associated with the plasma membrane-cytoskeleton complex, including the beaded filament, is ␣-crystallin (14 -18).…”

mentioning

confidence: 99%

Gene Structure and cDNA Sequence Identify the Beaded Filament Protein CP49 as a Highly Divergent Type I Intermediate Filament Protein

Hess

Casselman

Fitzgerald

1996

Journal of Biological Chemistry

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The fiber cell of the vertebrate ocular lens assembles a cytoskeletal structure, the beaded filament, which contains two proteins unique to the fiber cell: CP49 (phakinin) and CP115/CP95 (filensin). We report here the complete primary sequence and gene structure for human CP49. These data show that CP49 is a member of the intermediate filament family, but highly unusual in several regards. 1) CP49 primary sequence does not permit unambiguous assignment to any existing class of intermediate filament protein, but exhibits a gene structure that is identical to the Type I cytokeratins. 2) CP49 essentially lacks one of the three major domains that characterize all intermediate filament proteins, the carboxyl-terminal tail domain. 3) CP49 shows substitutions at 3 of 4 residues in the otherwise highly conserved intermediate filament protein motif LNDR. Notably, this divergence includes an Arg to Cys substitution that has only been observed in the mutant human cytokeratin K14, a mutation shown to cause the skin blistering seen in the genetic disorder Dowling-Meara epidermolysis bullosa simplex.

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“…The presence of vimentin-immunoreactive peptides smaller than the expected 56-57 kD is often presumed to represent products of the proteolysis of vimentin [2,[16][17][18], although there is no definitive evidence to support this presumption. Furthermore, several antibodies to the lens-specific intermediate filament phakinin react with peptides smaller than the expected 47-49 kD [2,6,9,[19][20][21][22]. Since our work involves describing extrinsic peptides associated with lens plasma membrane, we were interested in determining the identity of a peptide or peptides which react with both antivimentin and antiphakinin antibodies.…”

Section: Introductionmentioning

confidence: 99%

“…The cytoskeleton of lens fiber cells is composed of intermediate filaments composed of vimentin [1][2][3] and a lens-specific intermediate filament structure, the beaded filament [4], composed of 2 lens-specific members of the intermediate filament protein family, filensin and phakinin [5][6][7]. It is now apparent that changes in the composition and structure of the lens intermediate filament cytoskeleton are associated with normal processes such as aging, growth and differentiation [2,8,9] as well as the abnormal process of cataractogenesis [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Identification of a Vimentin-Reactive Peptide Associated with Ocular Lens Membranes as Cytokeratin

Brooks

Fleschner

2003

Ophthalmic Res

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We wished to identify a 44-kD peptide isolated from lens membrane fractions which has apparent immunoreactivity to antivimentin and to antiphakinin. Urea-soluble proteins from rat lens membrane fractions were separated by two-dimensional electrophoresis, transferred to polyvinylidene fluoride membranes and probed with monoclonal antibodies to vimentin or cytokeratins, or a polyclonal antibody to phakinin. The monoclonal antibody to vimentin recognized the expected protein (M_r = 56 kD, pI = 5.1) and several smaller and more acidic peptides including a 44-kD spot with a pI of 4.9. A similar pattern of immunoreactivity was found with commercially available purified vimentin. The polyclonal antibody to phakinin recognized the expected protein (M_r = 52 kD, pI = 5.0) and several smaller and more acidic peptides, including a 44-kD spot with a pI of 4.9. Matrix-assisted laser desorption ionization mass spectroscopy analysis of the tryptic digest of the spot corresponding to 44 kD and pI of 4.9 identified neither vimentin nor phakinin but did identify peptides derived from ovalbumin (added to samples as an internal standard) and cytokeratin 1. Antibodies which recognize cytokeratin 1 reacted weakly with a 44-kD peptide which comigrated with the 44-kD vimentin-immunoreactive peptide in adjacent lanes of single-dimension SDS polyacrylamide gels. The 44-kD acidic (pI = 4.9) peptide which reacts with a monoclonal antibody to vimentin may be derived from cytokeratin 1.

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A cytoskeletal protein unique to lens fiber cell differentiation

Cited by 100 publications

References 11 publications

Functions of the intermediate filament cytoskeleton in the eye lens

Functions of the intermediate filament cytoskeleton in the eye lens

Gene Structure and cDNA Sequence Identify the Beaded Filament Protein CP49 as a Highly Divergent Type I Intermediate Filament Protein

Identification of a Vimentin-Reactive Peptide Associated with Ocular Lens Membranes as Cytokeratin

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