HGNC Approved Gene Symbol: PPEF2
Cytogenetic location: 4q21.1 Genomic coordinates (GRCh38): 4:75,859,867-75,902,452 (from NCBI)
During random sequencing of human retina cDNAs, Sherman et al. (1997) identified a homolog of Drosophila rdgC. Full-length cDNAs of the gene, termed PPEF2, predicted a 753-amino acid protein that is 39% identical to that of Drosophila rdgC and has a domain structure similar to that of rdgC and PPEF1 (300109). Sherman et al. (1997) noted the existence of a shorter alternatively spliced form of PPEF2, termed PPEF2(S), that uses alternative splice acceptor sites in exons 5 and 14 and predicts a 598-amino acid protein lacking EF-hand domains. Northern blot analysis of rat tissues revealed a 3.7-kb PPEF2 mRNA in retina. In situ hybridization and cell fractionation experiments further revealed that the gene is expressed exclusively in the inner segments of the photoreceptor cells of the retina and in the pineal gland. Sherman et al. (1997) stated that the inner segment localization implies that PPEF2 probably does not dephosphorylate rhodopsin and is probably not directly involved in phototransduction.
By genomic analysis, Sherman et al. (1997) determined that the PPEF2 gene contains at least 15 exons spanning 33 kb.
Sherman et al. (1997) used Southern blot hybridization and PCR of human-rodent cell lines to map the PPEF2 gene to human chromosome 4.
Ramulu et al. (2001) produced mice carrying targeted disruptions in the Ppef1 and Ppef2 genes. By analyzing both single and double mutant mice, they observed that rod light responses and rhodopsin dephosphorylation kinetics were normal. Furthermore, there was no evidence of retinal degeneration in the PPEF mutant mice. Ramulu et al. (2001) concluded that in contrast to loss of rdgC function in Drosophila, elimination of PPEF function does not cause retinal degeneration in vertebrates.
Ramulu, P., Kennedy, M., Xiong, W.-H., Williams, J., Cowan, M., Blesh, D., Yau, K.-W., Hurley, J. B., Nathans, J. Normal light response, photoreceptor integrity, and rhodopsin dephosphorylation in mice lacking both protein phosphatases with EF hands (PPEF-1 and PPEF-2). Molec. Cell. Biol. 21: 8605-8614, 2001. [PubMed: 11713293] [Full Text: https://doi.org/10.1128/MCB.21.24.8605-8614.2001]
Sherman, P. M., Sun, H., Macke, J. P., Williams, J., Smallwood, P. M., Nathans, J. Identification and characterization of a conserved family of protein serine/threonine phosphatases homologous to Drosophila retinal degeneration C (rdgC). Proc. Nat. Acad. Sci. 94: 11639-11644, 1997. [PubMed: 9326663] [Full Text: https://doi.org/10.1073/pnas.94.21.11639]