Disease relevance of CKB

• At early stages of development (days 2-5), B-CK was more or less evenly distributed over the entire retina with the exception of ganglion cells, which were stained more strongly for B-CK than other retinal precursor cells [1].

High impact information on CKB

• M-CK molecules and translation products of chimeric cDNA molecules containing the head half of the B-CK and the tail half of the M-CK coding regions were localized in the M-band of the myofibrils [2].
• In the case of purified acetylcholine receptor-rich membranes, antibodies specific for chicken B-CK label only one face of the isolated vesicles [3].
• In the chicken, a high degree of heterogeneity at the protein level has been reported for the creatine kinase-type B (B-CK) [4].
• The transcription of the single hnRNA is directed by a complex promoter region containing a stretch of sequences which is highly conserved among all the B-CK genes known to date [4].
• Here we show that the two B-CK isoproteins, Ba- and Bb-CK, are encoded by two mRNAs, which are derived from a single copy gene by a stochastic alternative splicing mechanism [4].

Biological context of CKB

• cDNA clones for chicken B-CK were isolated by immunoscreening from a gizzard cDNA library constructed in the expression vector lambda gtll [5].
• COM184: a polymorphic microsatellite marker for CKB on chicken chromosome 5 [6].
• Interestingly, in limb mesenchyme cultures, significant M-CK expression was detected during chondrogenesis (days 2-7), whereas hypertrophic cells expressed only B-CK [7].
• Quantitation of the CK activity peak ratios of these two populations revealed the existence of a tissue-specific, post-translational mechanism regulating B-CK dimerization in neural tissues [8].
• Phosphorylation of Bb to yield Bb* is concluded to reduce the Km of B-CK dimers for CP by about 50% [9].

Anatomical context of CKB

• The B-CK cDNA hybridizes specifically to a 1.6-kb mRNA found in brain and gizzard but not in adult skeletal muscle tissue [10].
• The presence of mRNA coding for creatine kinase M (Mck) and creatine kinase B (B-CK) in RNA from myogenic and fibrogenic cell cultures, embryonic muscle, and embryonic brain tissue was demonstrated by "in vitro" translation in a heterologous cell-free protein-synthesizing system from rabbit reticulocytes [11].
• In tibial chondrocytes, an increase in B-CK expression was seen when the cells became hypertrophic [7].
• B-CK and Mib-CK were localized along the entire sperm tail and in the mitochondria-rich midpiece, respectively [12].
• In the growth plate, B-CK expression was highest in the most calcified regions, and M-CK was less abundant than B-CK in all regions of the growth plate [7].

Associations of CKB with chemical compounds

• In RNA from cells grown in 5-bromo-2'-deoxyuridine (BrdUrd) for 3 days and subcultured into the same medium for another 3 days only mRNA for B-CK was found [13].
• Expression of B-CK increased slightly over 15 days in mineralizing, retinoic acid-treated cephalic chondrocytes, but it decreased in nonmineralizing caudal chondrocytes, while there was little expression of M-CK [7].
• In addition to the two monomer subunits of chicken brain-type creatine kinase (B-CK, EC, 2.7.3.2), termed Bb (basic) and Ba (acidic), another subspecies called Bb* was identified by chromatofocussing in the presence of 8 M urea (Quest et al., ) [9].
• B-CK was phosphorylated after treating the cultures with 1-oleoyl-2-acetyl-sn-glycerol, dibutyryl-cAMP, okadiac acid and combinations thereof, but not with 1,2-dioleoyl-sn-glycerol [14].

Analytical, diagnostic and therapeutic context of CKB

• Isolated chicken B-CK can be resolved by two-dimensional gel electrophoresis into a major acidic Ba-CK and a major basic Bb-CK protein species which are very likely produced from the unique chicken B-CK gene (Wirz, T., Hossle, J [15].
• Proteolytically modified M-CK and B-CK subunits were able to refold and reassociate into dimeric structures after treatment with high concentrations of LiCl and at low pH [16].
• The two subunits were shown by peptide mapping, amino acid analysis and partial sequencing, as well as by immunological criteria, to be distinct B-CK polypeptides [8].
• These intestinal epithelial cell creatine kinases were indistinguishable from the cytoplasmic (B-CK) and mitochondrial (Mi-CK) creatine kinase isozymes of brain when compared by SDS-PAGE, cellulose polyacetate electrophoresis, and peptide mapping [17].
• The expression and the cellular- as well as subcellular-distribution of brain-type B-CK and mitochondrial Mi-CK during development of the chicken retina was studied by immunoblotting, immunofluorescence and immunogold methods [1].

References