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Scientific Newsletter

Editor's Notes

from literature on

Colour Pigment
(BCP, GCP, RCP)

Editor's Notes

Recent update from: 18.12.1999


RCP, GCP Notes

  • Pathogenic mechanisms blue cone monochromatism: deletion in the locus control region or genetic rearrangements
  • Deletion of exon 4 in a isolated RCP
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (5)


RCP, GCP Notes

  • Pro 307 Leu mutation
  • Diminished absorption of light and activation of GNT
  • Cause of color vision deficiency
  • Mutation does not impair transport of cone pigment to the cell membrane
  • P307 of cone pigment is homologue of P291 in RHO
  • The mutation disrupts the RAl binding pocket without disruption the helical conformation
  • Comparable to Pro 347 mutants
  • Spectral tuning by Ala 180, Phe 277 and Ala 285
Species: recombinant
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (8)


BCP, Blue Notes

Species: Homo sapiens
See also:
Chromosomal localisation in man: 7q22-qter

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (6)


BCP, Blue Notes

Species: Homo sapiens
See also:
Chromosomal localisation in man: 7q31-q35

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (4)


BCP, Blue Notes

Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data
gDNA: 17 kb
Exons: 5
Primers:
Protein Data
Aminoacids: 348 AA
Molecularweight on SDS-PAGE:

calculated:
Reference: (7)


BCP, blue Notes

  • Transgenic mice with 3.8 and 1.1 kb 5' sequence of human blue cone pigment
  • Transgene expression in S-cones and INL
  • Reporter-gene positive INL cells = Bipolars
  • Both constructs resulted in expression in S-cones like in wildtype animals
  • Cones make 5% of photoreceptors
  • Two cone types in mouse retina (middle wave = 510 nm, near UV= 370 nm)
Species: Mus musculus
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (1)


RCP, GCP, red, green Notes

  • Two highly expressed isoforms with cyclophilin and RBD4 domains
  • Cyclophilin-II identical to RanBP2, which binds small GTP binding protein Ran
  • Cyclophilin domain does not bind opsin directly, it stabilizes the interaction to RBD4 domain
  • Binding is GTP independent
  • No binding with RHO and BCP due to cyclophilin PPIase activity
  • No selection of phosphorylated forms
  • Cyclophilin functions as a chaperon and foldase
Species:
See also: RanBP2
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (3)


RCP, GCP, red, green Notes

  • Majority of red-green defects associated with deletion of GCP or formation of red-green or green-red 5'-hybrids
  • Protan defects are associated with red-green hybrids, rarely with green-red hybrids
  • Deuteranopia associated with complete GCP deletion and green-red fusions
  • Exon 5 mutations define red-green status of a hybrid
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers: GCP, RCP
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (2)


RCP, GCP, red, green Notes

  • Lack of glycosylation does neither impair the ability to absorb light of the appropriate wavelength nor to activate GNT
  • Glycosylation and palmitoylation are not required for the formation of cone visual pigments
  • Mutant: N32S green opsin
  • X-linked cone opsins are not palmitoylated unlike RHO
  • C203R mutatnt is unglycosylated, aberrantly folded and deficient in transport to the cell membrane
  • Lack of glycosylation in C203R seems to be an effect of misfolding and not vice versa
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (9)
Online Reference

RCP, GCP, red, green Notes

  • 41% identity to RHO
  • red green 96% identity
  • red green/blue 43% identity
  • green genes vary in copy number, single red gene
  • red to green in head to tail tandem array
  • integral membrane proteins, in plasma and disc membrane
  • absorption maxima: 420 nm blue, 530 nm green, 560 nm red
  • RCP, GCP exons 2-6 correspond to RHO exons
  • TATA-box
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data
cDNA:
Exons: 6
Primers:
Protein Data
Aminoacids: 364 AA
Molecularweight on SDS-PAGE: 47,1 kDa

calculated:
Reference: (7)


RCP, GCP, red, green Notes

  • Only expressed RCP-GCP hybrids cause deuteranomaly
  • Most males have one RCP and two GCP, rarely more than three GCP
  • LCR between 3.1 and 3.7 kb 5' of the RCP gene transcription initiation site
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers: RCP, GCP
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (11)


RCP, GCP, red, green Notes

  • anomalous trichromates: 3 types of cones, one with altered pigment
  • Dichromats: 2 types of cones
  • red-green coulour defects: 8% of all male caucasian
  • Dichromacy due to unequal exchanges or gene conversion producing red-green hybrids
Species: Homo sapiens
See also:
Chromosomal localisation in man: Xq22-q28

in mouse:
Gene Data

Exons: 6
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (6)


RCP, GCP, red, green Notes

  • Identification of cis-acting elements involved in expression
  • Postive element between -130 and TATA-box
  • LCR does not enhance transcription in transient transfection but binds factors that recognize proximal promotor region
  • 4 critical elements:
    1. GA-box (-130 to -113), positive effect, binds SP1 and SP3
    2. PCE1 (-109 to -93), photoreceptor specificity
    3. Region reducing promotor activity
    4. Conserved region -49 to -40
      1. Unlikely NRL activity
Species: Homo sapiens
See also:
Chromosomal localisation in man:

in mouse:
Gene Data

Exons:
Primers:
Protein Data
Aminoacids:
Molecularweight on SDS-PAGE:

calculated:
Reference: (10)


References:

1. Chen, J., Tucker, C.L., Woodford, B., Szel, A., Lem, J., Gianella Borradori, A., Simon, M.I., and Bogenmann, E. The human blue opsin promoter directs transgene expression in short-wave cones and bipolar cells in the mouse retina. 1994; Proc.Natl.Acad.Sci.U.S.A. 91: 2611 - 2615.
Goto Top

2. Deeb, S.S., Lindsey, D.T., Hibiya, Y., Sanocki, E., Winderickx, J., Teller, D.Y., and Motulsky, A.G. Genotype-phenotype relationships in human red/green color-vision defects: molecular and psychophysical studies. 1992; Am.J.Hum.Genet. 51: 687 - 700.
Goto Top

3. Ferreira, P.A., Nakayama, T.A., Pak, W.L., and Travis, G.H. Cyclophilin-related protein RanBP2 acts as chaperone for red/green opsin. 1996; Nature. 383: 637 - 640.
Goto Top Link to PudMed

4. Fitzgibbon, J., Appukuttan, B., Gayther, S., Wells, D., Delhanty, J., and Hunt, D.M. Localisation of the human blue cone pigment gene to chromosome band 7q31.3-32. 1994; Hum.Genet. 93: 79 - 80.
Goto Top Link to PudMed

5. Ladekjaer Mikkelsen, A.S., Rosenberg, T., and Jorgensen, A.L. A new mechanism in blue cone monochromatism. 1996; Hum.Genet. 98: 403 - 408.
Goto Top Link to PudMed

6. Nathans, J., Piantanida, T.P., Eddy, R.L., Shows, T.B., and Hogness, D.S. Molecular genetics of inherited variation in human color vision. 1986; Science. 232: 203 - 210.
Goto Top Link to PudMed

7. Nathans, J., Thomas, D., and Hogness, D.S. Molecular genetics of human color vision: the genes encoding blue, green, and red pigments. 1986; Science. 232: 193 - 202.
Goto Top Link to PudMed

8. Ostrer, H. and Kazmi, M.A. Mutation of a conserved proline disrupts the retinal-binding pocket of the X-linked cone opsins. 1997; Mol.Vis. 3: 16
Goto Top Link to PudMed
Human Mutation Online

9. Ostrer, H., Pullarkat, R.K., and Kazmi, M.A. Glycosylation and palmitoylation are not required for the formation of the X-linked cone opsin visual pigments. 1998; Mol.Vis. 4:28: 28
Goto Top Link to PudMed

10. Shaaban, S.A. and Deeb, S.S. Functional analysis of the promoters of the human red and green visual pigment genes. 1998; Invest.Ophthalmol.Vis.Sci. 39: 885 - 896.
Goto Top Link to PudMed

11. Yamaguchi, T., Motulsky, A.G., and Deeb, S.S. Visual pigment gene structure and expression in human retinae. 1997; Hum.Mol.Genet. 6: 981 - 990.
Goto Top Link to PudMed


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Dr. rer. medic. Markus Preising, Dipl.Biol.
Molecular Genetics Laboratory
Department of Paediatric Ophthalmology, Strabismology and Ophthalmogenetics
University of Regensburg
Head: Prof. Dr. med. Birgit Lorenz