CARKD

Carbohydrate kinase domain containing protein, also known as CARKD, is a human is_associated_with::protein of unknown function. The protein is conserved throughout many species, and has predicted orthologs through is_associated_with::eukaryotes, is_associated_with::bacteria, and is_associated_with::archea.

Gene
CARKD is located on is_associated_with::Chromosome 13 in humans. The following genes are near CARKD on the chromosome:
 * is_associated_with::COL4A2: A2 Subunit of type IV collagen
 * is_associated_with::RAB20: Potential regulator of Connexin 43 trafficking.
 * is_associated_with::CARS2: Mitochondrial Cystienyl-tRNA Synthetase 2
 * is_associated_with::ING1: Tumor-Suppressor Protein

Structure
This protein is part of the is_associated_with::phosphomethylpyrimidine kinase: is_associated_with::ribokinase / pfkB superfamily. This family is characterized by the presence of a domain shared by the family. CARKD contains a carbohydrate kinase domain. This family is related to and  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
 * is_associated_with::Isoelectric point: 9.377
 * CARKD orthologs have highly variable isoelectric points.
 * Post-translational modification: Three post-translational modifications are predicted:
 * Modified Phosphotyrosine Residue
 * Two N-Linked Glycosylation Sites
 * A Signal Peptide and signal peptide cleavage site was predicted.

Tissue distribution
CARKD appears to be ubiquitously expressed at high levels. Expression data in the human protein, and the mouse is_associated_with::ortholog, indicate its expression in almost all tissues. One peculiar expression pattern of CARKD is its differential expression through the development of is_associated_with::oligodendrocytes. Its expression is lower in oligodendrocyte progenitor cells than in mature oligodendrocytes.

Binding partners
The human protein apolipoprotein A-1 binding precursor (is_associated_with::APOA1BP) was predicted to be a binding partner for CARKD. 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, 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 is_associated_with::allele-specific expression of CARKD, CARKD may play a role in is_associated_with::acute lymphoblastic leukemia. In addition, microarray data indicates that CARKD is up-regulated in is_associated_with::Glioblastoma multiforme tumors.