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The structure and complete nucleotide sequence of the human cyclophilin 40 (PPID) gene
Insights
Researchers characterized the human cyclophilin 40 (hCyP40) gene, PPID, revealing its structure, promoter elements, and chromosomal location. This housekeeping gene is highly conserved across species, indicating its fundamental biological role.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Cyclophilin 40 (hCyP40) is a novel cyclophilin family member found in unactivated steroid hormone receptor complexes.
- It shares homology with FKBP59, another component of these receptor complexes.
Purpose of the Study:
- To isolate and sequence the entire human cyclophilin 40 (hCyP40) gene (PPID).
- To analyze the gene's structure, promoter region, and chromosomal localization.
- To investigate the evolutionary conservation of the hCyP40 gene.
Main Methods:
- Gene isolation and sequencing
- Exon-intron structure analysis
- 5' mRNA end determination using anchor-ligation PCR
- Promoter analysis (GC-rich, Sp1 sites)
- Chromosomal mapping via PCR with somatic cell hybrids
- Evolutionary conservation assessment using Zoo blot analysis
Main Results:
- The human hCyP40 gene (PPID) comprises 10 exons and 9 introns.
- Transcription initiation occurs upstream of the first ATG, with a promoter lacking TATA/CAAT boxes but containing Sp1 sites, typical of housekeeping genes.
- The hCyP40 gene is located on chromosome 4.
- The gene exhibits high evolutionary conservation across various species.
Conclusions:
- The human cyclophilin 40 (hCyP40) gene (PPID) has been fully characterized.
- Its promoter characteristics suggest a role as a housekeeping gene.
- The high evolutionary conservation underscores the functional importance of hCyP40.
Abstract:
Cyclophilin 40 is a recently identified member of the cyclophilin family that is found in an unactivated steroid hormone receptor complex. Cyclophilin 40 possesses a region homologous to FKBP59, a member of the FK506-binding protein family that is also a component of the receptor complex. We report the isolation and sequencing of the entire human cyclophilin 40 (hCyP40) gene (human gene symbol PPID). The gene contains 10 exons (43 to 698 bp) and 9 introns encompassing 14.2 kb. The exon organization of the cyclophilin-like region is not similar to that of the human cyclophilin A gene (PPIA), suggesting their early divergence in evolution. Determination of the sequence of the 5' end of the hCyP40 mRNA by an "anchor-ligation PCR" procedure showed that transcription is initiated from a cluster of sites about 80 bp upstream from the first in-frame ATG. The immediate 5'-flanking region of the gene lacks typical TATA and CAAT boxes, but is GC-rich and contains Sp1 sites, features characteristic of promoters associated with housekeeping genes. The hCyP40 gene was mapped to chromosome 4 by PCR with genomic DNA from somatic cell hybrids. As shown by "Zoo blot" analysis, the cyclophilin 40 gene appears to be highly conserved throughout evolution.