Identification and characterization of TMEM16E and TMEM16F genes in silico.

TMEM16A (FLJ10261 or ORAOV2) gene within the CCND1-FGF4-EMS1 amplicon at human chromosome 11q13.3 encodes transmembrane protein homologous to TMEM16B (C12orf3), TMEM16C (C11orf25), and TMEM16D (FLJ34272). Here, we identified novel TMEM16 family genes by using bioinformatics. Novel genes corresponding to DKFZp451A148 cDNA (AL833271.1) and 9330162L24 cDNA (AK034197.1) were designated human TMEM16E gene and mouse Tmem16e gene, respectively. Novel genes corresponding to DKFZp451M105 cDNA (AL832340.1) and F730003B03 cDNA (BC060732.1) were designated human TMEM16F gene and mouse Tmem16f gene, respectively. NELL1-TMEM16E locus at human chromosome 11p15.1-p14.3 and NELL2-TMEM16F locus at human chromosome 12q12 were paralogous regions within the human genome. TMEM16E mRNA was expressed in testis and pancreatic islet, while TMEM16F mRNA was expressed in embryonic stem cell, fetal liver, retina, chronic myelogenous leukemia, and intestinal cancer. TMEM16E (913 aa) and TMEM16F (892 aa) showed 50.3% total-amino-acid identity. Eight-transmembrane domains were identified within TMEM16E and TMEM16F proteins by using the TMHMM2 program. Phylogenetic analysis revealed that TMEM16E and TMEM16F constitute a subfamily among TMEM16 family proteins. TM16H1 domain around transmembrane domain 1 (TM1)-TM2, TM16H2 domain around TM5, and TM16H3 domain around TM6-TM7 were identified as conserved regions among TMEM16 family proteins. TMEM16 family members were eight-transmenbrane proteins with TM16H1-TM16H3 domains and a conserved Asn glycosylation site. This is the first report on TMEM16E and TMEM16F genes.