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Dystrophin related protein 2 (DRP2)

(last modified October 14, 2002)



Contents




Summary


The "dystrophin related protein 2 (DRP2)", was discovered by Roberts et al. when they tried to isolate reverse transcripts encoding C-terminal domains of dystrophin-like proteins from various animals using degenerate oligonucleotides. Because the novel sequences isolated from dogfish (a cartilaginous fish) and goby (a bony fish) were more closely related to each other than to human dystrophin and utrophin, the authors hypothesized that the sequences might be representatives of a novel protein from the dystrophin family. Subsequently, using a new set of DRP2-specific primers, the orthologous human and mouse sequences were successfully isolated. The DRP2 gene comprises 24 exons distributed over approximately 45 kb and maps to Xq22. The DRP2 mRNA, measuring ~7.7 kb, contains a 340 bp 5' untranslated region, a 2,862 bp open reading frame and a 3' untranslated region of about 3.9 kb (Roberts et al.). RT-PCR analysis showed DRP2 expression in all sections of murine brain, with higher levels in cortex, striatum, spinal cord and olfactory bulb (Roberts et al.).

All data presented below are taken from: Roberts, R.G., Freeman, T.C., Kendall, E., Vetrie, D.L.P., Dixon, A.K., Shawsmith, C., Bone, Q., and Bobrow, M. (1996). Characterization of DRP2, a novel human dystrophin homologue. Nature Genet. 13:223-226.


The DRP2 gene


Links to other databases:
Gene Symbol nomenclature   LocusLink db   OMIM Gene Map    GDB

The DRP2 gene comprises 24 exons distributed over approximately 45 kb. The gene maps to Xq22, approximately 300 kb proximal to the gene encoding a protein tyrosine kinase (btk) defective in X-linked agammaglobulinaemia. The DRP2 gene is transcribed in a proximal to distal direction (Roberts et al.).

Exon Exon size (bp) Intron size (kb) 5' cDNA position Splice after Remarks
1       - 5'UTR
2       - 5'UTR
3         5'UTR / .. bp coding
24         .. bp coding / 3'UTR

Legend:
Exon: numbering of exons and intron/exon boundaries are according to Roberts et al., with the first base of the Met-codon counted as position 1 (see ...). Exon size: size of exon indicated in basepairs. Intron size: size of intron indicated in kilobasepairs. 5' cDNA position: first base of the exon (according to cDNA sequence U43519). Splice after: splicing occurs in between of two coding triplets (0), after the first (1) or the second (2) base of a triplet. Remarks: 5'UTR = 5' untranslated region, 3'UTR = 3' untranslated region.


The DRP2 RNA


Links to other databases:   UniGene: Hs.159291

The DRP2 mRNA, measuring ~7.7 kb, could be detected on a Northern blot containing fetal brain poly(A)+ RNA. The mRNA contains a 340 bp 5' untranslated region, a 2,862 bp open reading frame and an 3' untranslated region of about 3.9 kb (Roberts et al.).

RT-PCR analysis showed DRP2 expression in all sections of murine brain, with higher levels in cortex, striatum, spinal cord and olfactory bulb (Roberts et al.). Expression could also be detected in epididymus, eye, ovary, testis and very weakly in colonic samples. No expression was detected in cardiac and skeletal muscle.


The DRP2 protein


Links to other databases:

The DRP2 protein sequence derived from the cDNA encodes 956... amino acids. It contains a short proline-rich N-terminal region (17% proline) followed by a sequence homologous to the last 2 spectrin-like repeats and the C-terminal domains of dystrophin and utrophin (Roberts et al.).

Evolution

Phylogenetic analysis of the dystrophin-like proteins shows that all groups, i.e. dystrophins, utrophins (DRP1s) and DRP2s, cluster together. Since utrophins and dystrophins have a higher homology to each other than to the DRP2s, they seem to have diverged more recently. Finally, the dystrophins, utrophins and DRP2s are more closely related to each other than to the dystrobrevins (the 87K tyrosine kinase substrate group).

Function

Sequence alignments show that the DRPs as a group have several conserved amino acid positions when compared to the dystrophins and utrophins. Most of these DRP2-specific sequences lie in regions which have been implicated in mediating interactions with ▀-dystroglycan and alpha1- and ▀1-synthropin. This suggests that DRP2 has specific interactions with other proteins or other members of these protein families.

The precise function of dystrophin and utrophin is still unclear, although both seem to be involved in membrane-cytoskeleton interactions at sites of membrane specialization and intercellular contact in various tissues. The observed homology with dystrophin and utrophin suggests that DRP2 has a similar function in areas of the central nervous system. The retention of the last two spectrin repeats indicates the possibility of a homo-dimerization.


DRP2 expression


RT-PCR analysis showed DRP2 expression in all sections of murine brain, with higher levels in in cortex, striatum, spinal cord and olfactory bulb (Roberts et al.). Expression could also be detected in epididymus, eye, ovary, testis and very weakly in colonic samples. No expression was detected in cardiac and skeletal muscle.


DRP2 and disease


Links to other databases:   OMIM: 300052

No disease has yet been associated with changes in the DRP2 gene.


Miscellaneous


DNA-primers:

Amplified Length Reference forward primer reverse primer Name
           

Legend:
Exonic sequences are in upper case, intronic and gene flanking sequences in lower case and added primer tails in italics. Amplified: region amplified. Numbering of exons is according to .... Length: length of PCR-product in basepairs. Reference: publication describing the primer(s). Forward primer: sequence of forward primer. Reverse primer: sequence of reverse primer. Name: name of the primers.


RNA-primers:

Amplified Length Reference Forward primer Reverse primer Name
           

Legend:
Exonic sequences are in upper case, intronic and gene flanking sequences in lower case and added primer tails in italics. Amplified: region amplified. Numbering of exons is according to .... Length: length of PCR-product in basepairs. Reference: publication describing the primer(s). Forward primer: sequence of forward primer. Reverse primer: sequence of reverse primer. Name: name of the primers.


DRP2 sequences




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