The human dopamine D2 receptor gene is located on chromosome 11 at q22-q23 and identifies a TaqI RFLP.

Human dopaminergic neurons are involved in the control of hormone secretion, voluntary movement, and emotional behavior. Mediating these effects are the dopamine D1 and D2 receptors. These macromolecules belong to a large family of related sequences known as the G protein-coupled receptors. The D2 receptors have been of special interest because they bind, with high affinity and specificity, many of the commonly prescribed antipsychotic drugs. We previously isolated a full-length cDNA clone of the rat D2 receptor. When a chromosome mapping panel was probed with the rat D2 receptor cDNA a 15-kb EcoRI restriction fragment was identified and localized to human chromosome 11. The rat cDNA was also used to clone a human genomic fragment, lambda hD2G1, which contains the last coding exon of the D2 receptor gene (DRD2) and 16.5 kb of 3' flanking sequence. Hybridization of lambda hD2G1 to a chromosome 11 regional mapping panel localized DRD2 to 11q. In situ hybridization of lambda hD2G1 to metaphase chromosomes refined this assignment to the q22-q23 junction of chromosome 11. A search for RFLPs associated with D2DR identified a frequent two-allele TaqI RFLP.     

C20orf9-003 (ACI-1), a gene localized on chromosome 20q13.12 encoding for a 49 kD cytoplasmic protein with a putative nucleotide binding site.

Murine NGD5 is a gene identified from NG108-15 cells which is postulated to be involved in opioid receptor function. Here we report the cloning and characterization of a cDNA C20orf9-003 (ACI-1) encoding the human orthologue of the mouse NGD5. Analysis of the genomic structure revealed that C20orf9-003 (ACI-1) contains 13 exons and 12 introns, spanning 52.5kb of genomic DNA and is a variant of C20orf9. Chromosomal localization of human C20orf9-003 (ACI-1) assigned this gene to chromosome 20q13.12. Genes at this locus have been associated with the progression and possibly the development of various cancers. In addition several linkage studies support the possibility that one or more genes affecting obesity are located in 20q13. No function can be clearly assigned to C20orf9-003 (ACI-1), however, the protein has a cytoplasmic subcellular location and the secondary structure contains a Rossman fold like feature which is found in many nucleotide binding proteins.     

Characterization of five novel human genes in the 11q13-q22 region

The redundancy of sequences in dbEST has approached a level where contiguous cDNA sequences of genes can be assembled, without the need to physically handle the clones from which the ESTs are derived. This is termed EST based in silico gene cloning. With the availability of sequence chromatogram files for a subset of ESTs, the quality of EST sequences can be ascertained accurately and used in contig assembly. In this report, we performed a study using this approach and isolated five novel human genes, C11orf1-C11orf5, in the 11q13-q22 region. The full open reading frames of these genes were determined by comparison with their orthologs, of which four mouse orthologs were isolated (c11orf1, c11orf2, c11orf3 and c11orf5). These genes were then analyzed using several proteomics tools. Both C11orf1 and C11orf2 are nuclear proteins with no other distinguishing features. C11orf3 is a cytoplasmic protein containing an ATP/GTP binding site, a signal peptide located in the N-terminus and a similarity to the C. elegans protein "Probable ARP 2/3 complex 20kD subunit." C11orf4 is a peptide which displays four putative transmembrane domains and is predicted to have a cytoplasmic localization. It contains signal peptides at the N- and C-termini. C11orf5 is a putative nuclear protein displaying a central coiled coil domain. Here, we propose that this purely EST-based cloning approach can be used by modestly sized laboratories to rapidly and accurately characterize and map a significant number of human genes without the need of further sequencing.     

Identification and characterization of C6orf37, a novel candidate human retinal disease gene on chromosome 6q14

We have identified a novel human gene, chromosome 6 open reading frame 37 (C6orf37), that is expressed in the retina and maps to human chromosome 6q14, a genomic region that harbors multiple retinal disease loci. The cDNA sequence contains an open reading frame of 1314 bp that encodes a 437-amino acid protein with a predicted molecular mass of 49.2 kDa. Northern blot analysis indicates that this gene is widely expressed, with preferential expression observed in the retina compared to other ocular tissues. The C6orf37 protein shares homology with putative proteins in R. norvegicus, M. musculus, D. melanogaster, and C. elegans, suggesting evolutionary conservation of function. Additional sequence analysis predicts that the C6orf37 gene product is a soluble, globular cytoplasmic protein containing several conserved phosphorylation sites. Furthermore, we have defined the genomic structure of this gene, which will enable its analysis as a candidate gene for chromosome 6q-associated inherited retinal disorders.     

GNB1L, a gene deleted in the critical region for DiGeorge syndrome on 22q11, encodes a G-protein beta-subunit-like polypeptide

CATCH 22 syndromes, which include DiGeorge syndrome and Velocardiofacial syndrome, are the most common cause of congenital heart disease which involve microdeletion of 22q11. Using a strategy including EST searching, PCR amplification and 5'-RACE, we have cloned a 1487 bp cDNA fragment from human heart cDNA library. The cloned GNB1L cDNA encodes a G-protein beta-subunit-like polypeptide, and the GNB1L gene is located in the critical region for DiGeorge syndrome. A comparison of GNB1L cDNA sequence with corresponding genomic DNA sequence revealed that this gene consists of seven exons and spans an approximately 60 kb genomic region. Northern blot analysis revealed GNB1L is highly expressed in the heart.     

The C1orf9 gene encodes a putative transmembrane member of a novel protein family

Here we report the characterization of a human mRNA encoding a novel protein denoted C1orf9 (chromosome 1 open reading frame 9). The cDNA sequence, derived from a testis cDNA library, contains 5700 bp which encodes an open reading frame of 1254 amino acids. The deduced protein contains a putative N-terminal signal peptide and one putative transmembrane region, indicating membrane localization. No significant homology was found with known characterized proteins. However, a 150 amino acid region has significant homology to deduced protein sequences from other organisms, including Caenorhabditis elegans (43% identity), Saccharomyces cerevisiae (47% identity), Schizosaccharomyces pombe (48% identity), and two proteins from Arabidopsis thaliana (42% and 40% identity), suggesting a novel family of conserved domains. The C1orf9 gene was assigned to chromosome 1q24. The gene spans approximately 78.7 kb and is organized into at least 24 exons. Expression analysis revealed a single C1orf9 mRNA species of approximately 6.0 kb with a predominant expression in pancreas and testis, and only low levels of expression in other tissues examined.