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PubMed1994

Biochemical and genetic analysis of variant C of caprine alpha s2-casein (Capra hircus).

Two alleles, A and B, were previously described at the goat alpha s2-casein locus. Isoelectric focusing allowed us to subdivide the former one in two new alleles, called A and C. Although alpha s2-casein C cannot actually be distinguished from its A counterpart by starch or polyacrylamide gel electrophoresis, it differs from the previous allele by a single substitution Lys (A)/Ile (C) at position 167, which was confirmed at the nucleotide level. The frequencies of the three alpha s2-casein alleles A, B and C were estimated to be 0.85, 0.04 and 0.11 in the French dairy breeds 'Alpine' and 'Saanen'.

Alleles↗

PubMed1997

Assignment of the casein kinase II gene family to cattle chromosomes.

Theileriosis, or East Coast fever, a parasitic disease in cattle, is associated with overexpression of casein kinase II. Casein kinase II is composed of two catalytic subunits (alpha or alpha') and two regulatory beta subunits. The genes encoding these subunits of casein kinase II were mapped to bovine chromosomes by polymerase chain reaction analysis of a well-characterized bovine x rodent somatic hybrid cell panel. The alpha-subunit (CSNK2A1) was mapped to bovine chromosome 13, the alpha'-subunit (CSNK2A2) to chromosome 5 and the beta-subunit (CSNK2B) to chromosome 23. Both CSNK2A1 and CSNK2B mapped to known regions of conserved synteny between human and cattle, while CSNK2A2 defined a new homology segment between the human and bovine genomes.

Animals↗

PubMed1981

Energy dispersive X-ray microanalysis of air dried casein micelles from bovine milk.

Secretory proteins (casein micelles) were air dried prior to elemental analysis either without treatment, following glutaraldehyde fixation and dialysis, or following dialysis against distilled water. Samples were then examined by energy dispersive X-ray microanalysis in a scanning transmission electron microscope (STEM). Untreated samples and samples dialysed against distilled water retain colloidal (bound) elements as compared to glutaraldehyde treated samples. Contamination of air dried casein micelles by ionic constituents in the non-protein aqueous phase was observed in the untreated sample and in the glutaraldehyde treated sample. Dialysis of casein micelles against distilled water reduced contamination from the aqueous phase without diminishing the apparent concentrations of colloidal elements.

Animals↗

PubMed1990

Occupational asthma caused by inhalation of casein.

Solutions of casein are usually sprayed over the leather in the final stage of tanning. We present the result of a thorough investigation of an atopic tannery worker with occupational asthma. Data from clinical record and metacholine challenges support the occupational source of the patient's symptoms, and positive bronchial challenge with casein clearly defines it as the specific aetiological agent. The presence of specific IgE suggests a hypersensitivity type I mechanism. In the tanning process chromium salts, paraphenylendiamine and formaldehyde have all been included as specific aetiological agents of asthma, but occupational asthma induced by inhalation of casein has not previously been reported.

Adult↗

PubMed1988

Purification and characterization of a casein-kinase-II-type enzyme from Xenopus laevis ovary. Biological effects on the meiotic cell division of full-grown oocyte.

A casein kinase of type II has been highly purified from Xenopus laevis ovary. A new experimental protocol has been developed for the purification, consisting in four chromatographic steps: hydrophobic on tyrosine-agarose, ion exchange on DEAE-Sepharose, affinity on heparin-Sepharose and fast protein liquid on Mono Q. The purification was greater than 20,000, taking into account an inhibitor present in the starting material which masked the activity in the crude fraction. The overall yield was greater than 20%. Full-grown Xenopus oocytes contain 64 milliunits per oocyte corresponding to an intracellular concentration in the nanomolar range. The enzyme shares the following features with the mammalian casein kinase II: (a) comparable subunit composition (42-kDa doublet, 38 kDa and 26 kDa), (b) autophosphorylation of the 26-kDa subunit, (c) ability to use GTP as well as ATP as phosphate donor, (d) inability to use Mn2+ instead of Mg2+ to support the activity, (e) phosphorylation of both threonine and serine residues of casein, (f) inhibition by low doses of heparin. Biological effects of the highly purified enzyme have been investigated upon microinjection into Xenopus full-grown oocytes. At nanomolar concentrations (approximately 3 nM) the enzyme inhibited progesterone induction of meiotic cell division whereas it facilitates meiotic maturation at the level of maturation-promoting factor. These results suggest a role for the kinase in the phosphorylation cascade involved during the prophase/metaphase transition of meiotic cell division, both in the mechanism of the meiotic prophase arrest and in the activity of the cytoplasmic factor maturation-promoting factor. When microinjected into oocytes above 45 nM, the kinase provoked complex changes in the profile of the in ovo 32P-labelled proteins indicating that its targets could be other kinase/phosphatase regulatory proteins.

Animals↗

PubMed1988

The disaggregation of calcium-depleted casein micelles.

The effect of depletion of Ca2+ on the composition and size distribution of casein micelles in milk has been examined using chemical analysis, size exclusion chromatography, fast protein liquid chromatography, turbidimetry and photon correlation spectroscopy. Partial removal of Ca2+ by EDTA and subsequent dialysis resulted in disaggregation of some of the casein micelles; as the EDTA concentration increased, the proportions of Ca2+ and phosphate relative to protein in the micelles remaining intact decreased. However, the composition of the intact micelles, with respect to the different caseins, and the number-frequency size distribution were essentially unchanged.

Animals↗

PubMed1989

Casein kinase II from Rana temporaria oocytes. Intracellular localization and activity during progesterone-induced maturation.

A homogeneous preparation of casein kinase II has been isolated from the ribosome-free extracts of Rana temporaria oocytes by means of chromatography on heparin-Sepharose, phosphocellulose and mono Q. The enzyme consists of three subunits with molecular mass of 43 kDa, 41 kDa and 29 kDa. The protein kinase was labelled with radioactive iodine and injected back into oocytes. As shown by histoautoradiography the enzyme forms a diffuse ring around the nucleus in the oocyte cytoplasm. A part of casein kinase II is found in informosomes. During oocytes maturation casein kinase II activity increases 7 h after progesterone administration and at the final stages of maturation (20-23 h). Cycloheximide blocks the second augmentation of kinase activity and does not influence the first one.

Animals↗

PubMed1990

Casein kinase II phosphorylates DNA-polymerase-alpha--DNA-primase without affecting its basic enzymic properties.

Immunoaffinity-purified DNA-polymerase-alpha--DNA-primase complex from calf thymus was phosphorylated in vitro by highly purified casein kinase II from the same tissue. Specific phosphorylation of the DNA-polymerizing alpha subunit and the primase-associated gamma subunit was observed. About 1 mol phosphate/mol polymerase--primase was incorporated. Despite this effect, neither the DNA polymerase nor the DNA primase activity were changed after phosphorylation by casein kinase II. Furthermore, dephosphorylation of polymerase--primase with alkaline phosphatase did not change the polymerase or the primase activity to a significant extent. Moreover, both alkaline phosphatase and casein kinase II had no effect on the processivity of DNA synthesis and on the lengths and amounts of primers formed by the DNA primase. Because DNA polymerase alpha maintained all its basic properties even after extensive treatment with alkaline phosphatase, it is unlikely that phosphorylation has a direct influence on the activities of the DNA-polymerase-alpha--DNA-primase complex. The possible influence of post-translational phosphorylation on the formation of a complex of polymerase alpha and its accessory proteins is discussed.

Animals↗

PubMed1992

The multimeric structure and disulfide-bonding pattern of bovine kappa-casein.

Bovine kappa-casein was analyzed by SDS/PAGE, MS and amino acid sequence analysis in order to determine its multimeric composition and disulfide-bonding pattern. SDS/PAGE revealed that kappa-casein in the native state can range in size from a monomer to a multimeric structure larger than a decamer. Three types of interchain disulfide linkage, Cys11-Cys11, Cys11-Cys88 and Cys88-Cys88, were all assigned in multimers purified from [14C]carboxymethylated and untreated bulk milk, as well as a milk sample from a kappa-casein-variant-B homozygote Co20. These results indicate that multimerization occurs in a random or at present unpredictable disulfide-bonding pattern regardless of the size of the multimer or the genotype.

Amino Acid Sequence↗

PubMed1995

Insert regions in domain X of the casein kinase II catalytic subunit.

Casein kinase II, cyclin-dependent kinases, and glycogen synthase kinase-3 are members of the protein kinase subfamily with a prominent insert in domain X of their catalytic subunit sequence. The function of the insert sequence in casein kinase II was investigated utilising synthetic peptides corresponding to the insert, cross-linking experiments, and the generation of casein kinase II insert region mutants. The mutation of basic residues (R276-->A, R278-->A, R281-->A, K277-->A) within the major insert sequence (PRFHDILQRHSRKRWERFVHSDNQHL, positions 265-290) did not affect alpha/beta subunit association, enzyme tetramerisation, thermal stability, and peptide (RRRDDDSDDD-NH2) phosphorylation. Similarly, replacement of residues 276-290 within the major insert with the corresponding residues from the cell-cycle kinase cyclin-dependent kinase 2 (CDK2) (FPKWKPGSLASHVKN) had no significant effect. The mutation of charged residues (H232-->A, H234-->A, D235-->A) within a nearby minor insert sequence (HGHDNY, positions 232-237), or replacement of residues 234-237 with the corresponding residues from CDK2 (DSEI) also did not affect alpha/beta subunit association and tetramerisation, but reduced enzyme thermal stability to more closely resemble the stability of the isolated alpha-subunit. In addition, mutations within the minor insert caused approximately a threefold increase in the apparent Km for peptide substrate. The results indicate that the major and minor inserts are not essential for alpha/beta subunit association, but the minor insert region influences substrate binding and thermal stability.

Amino Acid Sequence↗

PubMed1995

Site-directed mutagenesis and structure/function studies of casein kinase II correlate stimulation of activity by the beta subunit with changes in conformation and ATP/GTP utilization.

Casein kinase II exists in vivo as an active holoenzyme consisting of catalytic alpha and/or alpha' and regulatory beta subunits, which form a tetrameric structure of alpha 2 beta 2. Unlike most other protein kinases, casein kinase II uses both ATP and GTP effectively as phosphate donors. Two residues unique to the catalytic subunit of casein kinase II, Val66 and Trp176, were mutated to Ala66 and Phe176, respectively, the amino acids present in more than 95% of the identified protein kinase sequences. Using recombinant alpha subunit expressed in Escherichia coli, the mutations have been previously shown to reduce the utilization of GTP by changing Km values for ATP and GTP and to reduce the approximate fivefold stimulation observed upon addition of the regulatory subunit [Jakobi, R. & Traugh, J. A. (1992) J. Biol. Chem. 267, 23,894-23,902]. In this study, the mutations are shown to affect the catalytic activity of the reconstituted holoenzyme by changing both Km and Vmax values. The Vmax for ATP is reduced by the mutation of Trp176 to phenylalanine, but no change is observed with GTP. The Val66 to alanine and Val66/Trp176 to alanine/phenylalanine mutations reduce the Vmax values for ATP and GTP to levels comparable to those of the catalytic subunits alone, indicating that changes in the stimulation of activity by the beta subunit are due to changes in Vmax. Structural studies using ultraviolet CD spectroscopy show that changes in stimulation of Vmax by the beta subunit are correlated with changes in the secondary structure; the extent of these changes is reduced by both mutations. Correlation of changes in secondary structure and stimulation of activity by the beta subunit indicate that the formation of the wild-type holoenzyme causes conformational changes in the active site, leading to an increased rate of reaction. As shown by the mutations, Val66 and Trp176 are involved both in the conformational changes and in the selectivity of ATP and GTP.

Adenosine Triphosphate↗

PubMed2005

Potential benefit from using the alpha(s1)-casein genotype information in a selection scheme for dairy goats.

A stochastic approach is proposed to predict responses to selection when using alpha(s1)-casein genotype information in a selection scheme of a Spanish breed of dairy goats. Two independent selection objectives were considered: protein yield (PY), where the major additive gene CSN1S1, which codes for alpha(s1)-casein, has a small effect, and protein content (P%), where this gene has a large effect on performances. Significant differences in response between using and ignoring information on the major gene were observed only when the major gene has a large effect. The main result was in the case of P%, the total genetic gain obtained in the early generations of selection was maintained in the long-term. Taking account of genotype information either in the evaluation model or in the selection criteria leads to a faster fixation of the favourable allele and a reduction of the total genetic variance over generations. The inbreeding rates varied across generations, the highest rates observed in later generations of selection and when the major gene has a large effect and its genotype was included in the genetic evaluation procedure. It is concluded that inclusion of the casein genotype as an additional selection criteria will improve gains for protein traits, in particular P%. Recommendations are also given in order to optimize the use of this molecular information in dairy goat selection programs.

Alleles↗

PubMed1989

Phosphorylation of tubulin by casein kinase II regulates its binding to a neuronal protein (NP 185) associated with brain coated vesicles.

We recently described a new protein associated exclusively with neuronal clathrin-coated vesicles (CCVs), and characterized two monoclonal antibodies that react with it (S-8G8 and S-6G7). In this report, the association of neuronal protein of 185 kilodaltons (NP185) with CCV kinases and its interaction with tubulin are described. The affinity of NP185 for tubulin is significantly enhanced when tubulin is phosphorylated by CCV-associated casein kinase II. In contrast, phosphorylation of tubulin by a kinase activity associated with purified brain tubulin decreases its affinity for NP185. Together, these data suggest that the interaction of NP185 with tubulin is modulated by protein phosphorylation. Recent evidence has suggested that tubulin is phosphorylated by casein kinase II during neurite development. The enhanced affinity of NP185 for tubulin phosphorylated by casein kinase II could be important for proper intracellular sorting of this protein in the developing neuron.

Adaptor Proteins, Vesicular Transport↗

PubMed1992

A casein kinase-like kinase phosphorylates beta-tubulin and may be a microtubule-associated protein.

The hypothesis that casein kinase II (CKII) is a microtubule-associated protein kinase was investigated using a neuronal cell line and bovine brain. Heparin, an inhibitor of CKII, inhibited the phosphorylation of a PC12 cytosolic protein whose molecular weight was similar to that of beta-tubulin. Partially purified PC12 CKII was immunoreactive to an antibody directed against bovine CKII and was able to phosphorylate purified beta-tubulin in a heparin-inhibitable manner when the concentration of tubulin was less than 50 micrograms/ml. To better determine if CKII is a microtubule-associated protein kinase, bovine brain tubulin was chromatographed on FPLC Mono Q and phosphocellulose columns. Several tubulin casein kinase (TCK) activities were apparent. All TCK activities phosphorylated tubulin and casein, but none was able to phosphorylate the CKII-specific synthetic peptide RRREEETEEE. One of these TCK fractions was immunoreactive to the antibody directed against CKII, and this antibody labeled a 50-kDa molecular mass band that had a molecular mass distinctly different from those of the subunits of CKII. Thus, we suggest that a CKII-like protein, but not CKII, might be a microtubule-associated protein.

Amino Acid Sequence↗

PubMedDate not supplied

YI-S, a casein-free medium for axenic cultivation of Entamoeba histolytica, related Entamoeba, Giardia intestinalis and Trichomonas vaginalis.

Pancreatic digests of casein are major ingredients of media used in the axenic cultivation of lumen-dwelling parasitic protozoa, especially Entamoeba, Giardia, and trichomonads. The digest used almost exclusively in the development of these media, Medo-Peptone (Trypticase BBL), has not been available since 1981. Moreover, none of dozens of similar type digests tested since then in our laboratory has proved equal to Medo-Peptone, and in the last two years it has become increasingly difficult to obtain new batches which will support even modest growth of Entamoeba histolytica. In response to this problem we have developed a casein-free medium, YI-S, consisting of a nutrient broth, vitamin mixture and serum. We recommend it as a replacement for the casein-dependent medium TYI-S-33, currently the most widely used for axenic culture of Entamoeba histolytica and other lumen-dwellers.

Animals↗

PubMedDate not supplied

Anticariogenic complexes of amorphous calcium phosphate stabilized by casein phosphopeptides: a review.

Using laboratory, animal, and human in situ caries models, investigators have shown that casein phosphopeptide amorphous calcium phosphate complexes (CPP-ACP) exhibit an anticariogenic activity. The casein phosphopeptides (CPP) are produced from a tryptic digest of the milk protein casein by aggregation with calcium phosphate and purification by ultrafiltration. The CPP have a remarkable ability to stabilize calcium phosphate in solution and substantially increase the level of calcium phosphate in dental plaque. Through their multiple phosphoseryl residues, the CPP bind to forming clusters of amorphous calcium phosphate (ACP) in metastable solution, preventing their growth to the critical size required for nucleation and precipitation. The proposed mechanism of anticariogenicity for the CPP-ACP is that they localize ACP in dental plaque, which buffers the free calcium and phosphate lon activities, thereby helping to maintain a state of supersaturation with respect to tooth enamel depressing demineralization and enhancing remineralization. The CPP-ACP, unlike fluoride, can be added to sugar-containing foods and therefore have commercial potential as an additive to foods as well as to toothpastes and mouthwashes for the control of dental caries.

Amino Acid Sequence↗

PubMed1991

Intracellular degradation of newly synthesized casein in perfused rat mammary gland.

Degradation of newly synthesized casein in rat mammary gland perfused in situ was measured by a pulse-chase method using [3H]proline. Casein degradation during secretion was observed in the absence of prolactin, but not with prolactin present. Partial inhibition by chloroquine showed that hormone-dependent degradation occurred intracellularly by a lysosomal mechanism. The study indicates that this post-translational mechanism is a physiological regulator of net casein secretion.

Adenosine Triphosphate↗

PubMed1995

Casein kinase II alpha transgene-induced murine lymphoma: relation to theileriosis in cattle.

Infection of cattle with the protozoan parasite Theileria parva results in a fatal lymphoproliferative syndrome that is associated with the overexpression of casein kinase II. The role of this enzyme in the pathogenesis of lymphoproliferative disorders was investigated by expressing the catalytic subunit in lymphocytes of transgenic mice. Adult transgenic mice displayed a stochastic propensity to develop lymphoma; co-expression of a c-myc transgene in addition to casein kinase II resulted in neonatal leukemia. Thus, the casein kinase II gene can serve as an oncogene, and its dysregulated expression is capable of transforming lymphocytes in a two-step pathway with c-myc.

Amino Acid Sequence↗