To. Yarovinsky et al., Expression of the protein tyrosine phosphatase, phosphatase of regenerating liver 1, in the outer segments of primate cone photoreceptors, MOL BRAIN R, 77(1), 2000, pp. 95-103
Foveal cone photoreceptors are morphologically distinct and, presumably, ex
press unique transcripts. We have identified a cDNA clone encoding the prot
ein tyrosine phosphatase (PTP), phosphatase of regenerating liver 1 (PRL-1)
in a screen for genes that are enriched in monkey fovea. PRL-1 was origina
lly isolated as an immediate early gene in regenerating liver [R.H. Diamond
, D.E. Cressman, T.M. Laz, C.S. Abrams, R. Taub, PRL-1, a unique nuclear pr
otein tyrosine phosphatase, affects cell growth, Mel. Cell Biol. 14 (1994)
3752-3762]. On cDNA Southern blots of human and monkey retina, radiolabeled
PRL-1 cDNA hybridized to a single mRNA species of about 2.5 kb that was mo
st intense in fovea-enriched samples. The monkey PRL-1 deduced amino acid s
equence is identical to human, rat and mouse PRL-1. Affinity-purified antib
odies directed against PRL-1 preferentially labeled cone photoreceptor cell
s and a subpopulation of bipolar cells in monkey retina. Immunoreactivity i
n cones was confined to red and green, but not to blue, cones and was restr
icted to the outer segments. Immunolocalization also revealed that PRL-1 pr
otein expression was non-nuclear, suggesting that its function in the retin
a may be unrelated to its role in other tissues where it is expressed prima
rily in nuclei. Although both foveal and extrafoveal cones were PRL-1 react
ive, the high abundance of PRL-1 mRNAs detected in monkey fovea correlates
with the high concentration of cones in the fovea. The PRL-1 gene is locate
d on chromosome 6q within an interval that also contains the genes that cau
se two hereditary retinal dystrophies. These studies demonstrate novel expr
ession of the PRL-1 gene in the neural retina and suggest the phosphatase a
ctivity of PRL-1 may modulate normal cone photoreceptor cell function. (C)
2000 Elsevier Science BN. All rights reserved.