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Analysis of small GTP-binding proteins of the lens by GTP overlay assay reveals the presence of unique GTP-binding proteins associated with fiber cells.

Publication ,  Journal Article
Rao, PV; Zigler, JS; Garland, D
Published in: Exp Eye Res
February 1997

Low molecular weight GTP-binding proteins are molecular switches which are thought to play pivotal roles in cell growth, differentiation, cytoskeletal organization and vesicular trafficking. In this study, members of this family of proteins have been identified and characterized in the eye lens, for the first time. [alpha 33P]GTP blot overlay assays of monkey and human lens water soluble and membranous insoluble fractions revealed the presence of specific GTP-binding proteins in the range of 20-30 kDa (small GTPases) in both fractions, with much higher amounts in the membranous insoluble fraction. In the insoluble fraction, in addition to 20-30 kDa GTPases, there are three distinct GTP-binding proteins, ranging from 33-45 kDa. The small GTPases (20-30 kDa) were present throughout the lens in epithelium, cortex and nucleus, while the 33-45 kDa GTP-binding protein bands were exclusively associated with the cortex and nucleus (fiber cells). Analysis of lens fractions by two-dimensional electrophoresis, immunoprecipitation using monoclonal and sequence specific polyclonal antibodies and C3 exoenzyme mediated ADP-ribosylation demonstrated the presence of Ras, Rap, Rho, Rac, Rab and several other small GTPases. The 33-45 kDa GTP-binding proteins that are associated with lens fiber cells appear to be distinct from the small GTPases and from heterotrimeric GTPases, and were not detected in brain or heart tissue. The presence of different complements of GTP-binding proteins in lens fibers and epithelial, cells suggests their involvement in important regulatory functions, possibly related to cell growth, differentiation and organization of the cytoskeleton.

Duke Scholars

Published In

Exp Eye Res

DOI

ISSN

0014-4835

Publication Date

February 1997

Volume

64

Issue

2

Start / End Page

219 / 227

Location

England

Related Subject Headings

  • Ophthalmology & Optometry
  • Molecular Weight
  • Macaca mulatta
  • Lens, Crystalline
  • Lens Nucleus, Crystalline
  • Lens Cortex, Crystalline
  • Lens Capsule, Crystalline
  • Humans
  • GTP-Binding Proteins
  • Electrophoresis, Polyacrylamide Gel
 

Citation

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Rao, P. V., Zigler, J. S., & Garland, D. (1997). Analysis of small GTP-binding proteins of the lens by GTP overlay assay reveals the presence of unique GTP-binding proteins associated with fiber cells. Exp Eye Res, 64(2), 219–227. https://doi.org/10.1006/exer.1996.0197
Rao, P. V., J. S. Zigler, and D. Garland. “Analysis of small GTP-binding proteins of the lens by GTP overlay assay reveals the presence of unique GTP-binding proteins associated with fiber cells.Exp Eye Res 64, no. 2 (February 1997): 219–27. https://doi.org/10.1006/exer.1996.0197.
Rao, P. V., et al. “Analysis of small GTP-binding proteins of the lens by GTP overlay assay reveals the presence of unique GTP-binding proteins associated with fiber cells.Exp Eye Res, vol. 64, no. 2, Feb. 1997, pp. 219–27. Pubmed, doi:10.1006/exer.1996.0197.
Journal cover image

Published In

Exp Eye Res

DOI

ISSN

0014-4835

Publication Date

February 1997

Volume

64

Issue

2

Start / End Page

219 / 227

Location

England

Related Subject Headings

  • Ophthalmology & Optometry
  • Molecular Weight
  • Macaca mulatta
  • Lens, Crystalline
  • Lens Nucleus, Crystalline
  • Lens Cortex, Crystalline
  • Lens Capsule, Crystalline
  • Humans
  • GTP-Binding Proteins
  • Electrophoresis, Polyacrylamide Gel