CARKD
Protein-coding gene in humans
From Wikipedia, the free encyclopedia
Carbohydrate kinase domain containing protein (abbreviated as CARKD), encoded by CARKD gene, is a human protein of unknown function. The CARKD gene encodes proteins with a predicted mitochondrial propeptide (mCARKD), a signal peptide (spCARKD) or neither of them (cCARKD). Confocal microscopy analysis of transfected CHO (Chinese-hamster ovary) cells indicated that cCARKD remains in the cytosol, whereas mCARKD and spCARKD are targeted to the mitochondria and the endoplasmic reticulum respectively.[6] The protein is conserved throughout many species, and has predicted orthologs through eukaryotes, bacteria, and archea.
| NAXD | |||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | NAXD, LP3298, CARKD, NAD(P)HX dehydratase, PEBEL2 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 615910; MGI: 1913353; HomoloGene: 6333; GeneCards: NAXD; OMA:NAXD - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||
| Carbohydrate kinase | |||||||
|---|---|---|---|---|---|---|---|
 Crystallographic structure of a putative Bacillus subtilis carbohydrate kinase (rainbow colored, N-terminus = blue, C-terminus = red).[5] | |||||||
| Identifiers | |||||||
| Symbol | Carb_kinase | ||||||
| Pfam | PF01256 | ||||||
| Pfam clan | CL0118 | ||||||
| InterPro | IPR000631 | ||||||
| PROSITE | PDOC00806 | ||||||
| SCOP2 | 1kyh / SCOPe / SUPFAM | ||||||
| |||||||
Structure
Gene
Human CARKD gene has 10 exons and resides on Chromosome 13 at q34. The following genes are near CARKD on the chromosome:[7]
Protein
This protein is part of the phosphomethylpyrimidine kinase: ribokinase / pfkB superfamily. This family is characterized by the presence of a domain shared by the family.[8] CARKD contains a carbohydrate kinase domain (Pfam PF01256).[8] This family is related to Pfam PF02210 and Pfam PF00294 implying that it also is a carbohydrate kinase.
Predicted properties
The following properties of CARKD were predicted using bioinformatic analysis:
- Molecular Weight: 41.4 KDal[9]
- Isoelectric point: 9.377[10]
- CARKD orthologs have highly variable isoelectric points.[10]
- Post-translational modification: Three post-translational modifications are predicted:
- Modified Phosphotyrosine Residue[11]
- Two N-Linked Glycosylation Sites[11]
- A Signal Peptide and signal peptide cleavage site was predicted.[12]
Function
Tissue distribution
CARKD appears to be ubiquitously expressed at high levels. Expression data in the human protein, and the mouse ortholog, indicate its expression in almost all tissues.[13][14] One peculiar expression pattern of CARKD is its differential expression through the development of oligodendrocytes. Its expression is lower in oligodendrocyte progenitor cells than in mature oligodendrocytes.[15]
Binding partners
The human protein apolipoprotein A-1 binding precursor (APOA1BP) was predicted to be a binding partner for CARKD.[16] This prediction is based on co-occurrence across genomes and co-expression. In addition to these data, the orthologs of CARKD in E. coli contain a domain similar to APOA1BP. This indicates that the two proteins are likely to have originated from a common evolutionary ancestor and, according to Rosetta stone analysis theory,[17] are likely interaction partners even in species such as humans where the two proteins are not produced as a single polypeptide.
Clinical significance
Based on allele-specific expression of CARKD, CARKD may play a role in acute lymphoblastic leukemia.[18] In addition, microarray data indicates that CARKD is up-regulated in Glioblastoma multiforme tumors.[19]
Mutations of the NAXD gene cause the rare disease early-onset progressive encephalopathy with brain edema and/or leukoencephalopathy-2 (PEBEL2).