• Development and Reproduction
• /
• v.4 no.1
• /
• pp.87-93
• /
• 2000

Equine chorionic gonadotropin (eCG) consists of highly glycosylated noncovalently linked $\alpha$- and $\beta$-subunits and belongs to the glycoprotein hormone family that includes lutropin (LH), follitropin (FSH), and thyrotropin (FSH). eCG is a unique member of the gonadotropin family because it elicits response characteristics of both FSH and LH in other species than the hone. eCG is synthesized and secreted by trophoblastic cells of the endometial cups between 40 and 130 days of gestation. In the present study, mRNA expression ratio of eCG, eLH and eFSH $\alpha$- and $\beta$-subunints was investigated in the placenta and pituitary. mRNA was extracted from equine placenta on day 70 of gestation and from pituitary of male horse (27 month-old). When the expression of both subunit mRNAs of eCG in the equine placenta was compared by Northern blotting, the expression of the $\beta$ -subunit mRNA was relatively greater than that of the $\alpha$-subunit. And mRNA expression of $\alpha$-, LH $\beta$- and FSH $\beta$-subunits was analysed in the equine pituitary. An $\alpha$-subunit was revealed with a size of approximately 0.8 kb. FSH $\beta$-subunit mRNA also was detected out 1.8 kb. It is the same size of the FSH $\beta$ -subunit mRNA cloned. The intensity of $\alpha$-subunit mRNA was greater than that of the $\beta$-subunit suggesting that the expression of $\alpha$ -subunit was dominant in the equine anterior pituitary. Thus, the subunit mRNA levels seem to be independently regulated and their imbalance may account for differences in the quantities of $\alpha$- and $\beta$-subunits in the equine placenta and pituitary.

• Molecules and Cells
• /
• v.38 no.10
• /
• pp.866-875
• /
• 2015

COPI vesicles are essential to the retrograde transport of proteins in the early secretory pathway. The COPI coatomer complex consists of seven subunits, termed ${\alpha}-$, ${\beta}-$, ${\beta}^{\prime}-$, ${\gamma}-$, ${\delta}-$, ${\varepsilon}-$, and ${\zeta}$-COP, in yeast and mammals. Plant genomes have homologs of these subunits, but the essentiality of their cellular functions has hampered the functional characterization of the subunit genes in plants. Here we have employed virus-induced gene silencing (VIGS) and dexamethasone (DEX)-inducible RNAi of the COPI subunit genes to study the in vivo functions of the COPI coatomer complex in plants. The ${\beta}^{\prime}-$, ${\gamma}-$, and ${\delta}$-COP subunits localized to the Golgi as GFP-fusion proteins and interacted with each other in the Golgi. Silencing of ${\beta}^{\prime}-$, ${\gamma}-$, and ${\delta}$-COP by VIGS resulted in growth arrest and acute plant death in Nicotiana benthamiana, with the affected leaf cells exhibiting morphological markers of programmed cell death. Depletion of the COPI subunits resulted in disruption of the Golgi structure and accumulation of autolysosome-like structures in earlier stages of gene silencing. In tobacco BY-2 cells, DEX-inducible RNAi of ${\beta}^{\prime}$-COP caused aberrant cell plate formation during cytokinesis. Collectively, these results suggest that COPI vesicles are essential to plant growth and survival by maintaining the Golgi apparatus and modulating cell plate formation.

• The Korean Journal of Physiology and Pharmacology
• /
• v.18 no.2
• /
• pp.155-161
• /
• 2014

Overexpression of amyloid precursor protein with the Swedish mutation causes abnormal hyperphosphorylation of the microtubule-associated protein tau. Hyperphosphorylated isoforms of tau are major components of neurofibrillary tangles, which are histopathological hallmarks of Alzheimer's disease. Protein phosphatase 2A (PP2A), a major tau protein phosphatase, consists of a structural A subunit, catalytic C subunit, and a variety of regulatory B subunits. The B subunits have been reported to modulate function of the PP2A holoenzyme by regulating substrate binding, enzyme activity, and subcellular localization. In the current study, we characterized regulatory B subunit-specific regulation of tau protein phosphorylation. We showed that the PP2A B subunit PPP2R2A mediated dephosphorylation of tau protein at Ser-199, Ser-202/Thr-205, Thr-231, Ser-262, and Ser-422. Down-regulation of PPP2R5D expression decreased tau phosphorylation at Ser-202/Thr-205, Thr-231, and Ser-422, which indicates activation of the tau kinase glycogen synthase kinase 3 beta ($GSK3{\beta}$) by PP2A with PPP2R5D subunit. The level of activating phosphorylation of the $GSK3{\beta}$ kinase Akt at Thr-308 and Ser-473 were both increased by PPP2R5D knockdown. We also characterized B subunit-specific phosphorylation sites in tau using mass spectrometric analysis. Liquid chromatography-mass spectrometry revealed that the phosphorylation status of the tau protein may be affected by PP2A, depending on the specific B subunits. These studies further our understanding of the function of various B subunits in mediating site-specific regulation of tau protein phosphorylation.

• BMB Reports
• /
• v.36 no.4
• /
• pp.344-348
• /
• 2003

Protein kinase CKII is composed of two catalytic ($\alpha$ or $\alpha$') subunits and two regulatory ($\beta$) subunits. The $CKII{\beta}$ subunit is thought to mediate the tetramer formation and interact with other target proteins. However, its physiological function remains obscure. In this study, point mutants of $CKII{\beta}$ that are defective for the L41 binding were isolated by using the reverse two-hybrid system. A sequence analysis of the point mutants revealed that Asp-26, Met-52, and Met-78 of $CKII{\beta}$ are critical for L41 binding; Asn-67 (and/or Lys-139) and Met-52 are important for $CKII{\beta}$ homodimerization. Two point mutants, R75 and R83, of $CKII{\beta}$ interacted with L5, topoisomerase $II{\beta}$, and CKBBP1/SAG, but not with the wild-type $CKII{\beta}$. This indicates that $CKII{\beta}$ homodimerization is not a prerequisite for its binding to target proteins. These $CKII{\beta}$ point mutants may be useful in exploring the biochemical physiological functions of $CKII{\beta}$.

• Molecules and Cells
• /
• v.19 no.1
• /
• pp.124-130
• /
• 2005

Protein kinase CKII is composed of two catalytic (${\alpha}$ or ${\alpha}^{\prime}$) subunits and two regulatory (${\beta}$) subunits. The ${\beta}$ subunit mediates tetramer formation through ${\beta}-{\beta}$ homodimerization and ${\alpha}-{\beta}$ heterodimerization. In a previous study R26 and R75, point mutants of $CKII{\beta}$ defective in ${\beta}-{\beta}$ dimerization, were isolated. In the present work we characterized these $CKII{\beta}$ mutants in vitro. Purified R26 and R75 bound to $CKII{\alpha}$ but were defective in binding to $CKII{\beta}$. R75 stimulated the catalytic activity of CKII whereas R26 gave little stimulation, and poly-L-lysine increased the stimulation of catalytic activity by R26 or R75. Circular dichroism and intrinsic fluorescence data pointed to different conformational changes in R26 and R75. Molecular modeling of these mutants provides an explanation of the difference in their ability to interact with $CKII{\beta}$ and to activate $CKII{\alpha}$.

• BMB Reports
• /
• v.32 no.2
• /
• pp.189-195
• /
• 1999

From the Panax ginseng chloroplast, the psbE and psbF genes, encoding the $\alpha$- and $\beta$-subunits of cytochrome b-559 of the photosystem II reaction center, respectively, were cloned and characterized. The psbE and psbF genes were composed of 252 and 117 nucleotides, respectively. The deduced amino acid sequence of the $\alpha$-subunits showed 95%, 93%, and 91% homology to monocots, dicots, and liverwort, respectively, whereas the $\beta$-subunits showed approximately 98% to 95% homology to the same species. Southern blot analysis revealed that a single copy of the psbEF gene exists in the chloroplast plastid. Northern blot analysis indicated that the psbE and psbF genes are cotranscribed as a polycistron.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.5
• /
• pp.819-825
• /
• 2002

Methanol dehydrogenase (MDH) is a key enzyme in the process of methanol oxidation in methylotrophic bacteria. However, information on MDH genes from genus Methylobacillus is limited. In this study, a 6.5-kb HindIII DNA fragment of Methylobacillus sp. SK-5 chromosomal DNA was isolated from the genomic library of the strain by using a degenerate oligonucleotide probe that was designed based on JV-terminal amino acid sequence of the MDH $\alpha$ subunit purified from the strain. Molecular analysis of the fragment revealed four tightly clustered genes (mxaFJGI) involved in the methanol oxidation. The first and fourth genes were very similar to mxaF (77% identity for nucleotides an 78% identity for amino acids) and mxaF (67% Identity for nucleotides and 68% Identity for amino acids) genes, respectively, from Methylovorus sp. SSI. Genes mxaF and mxaI encode $\alpha$ and $\beta$ subunits of MDH, respectively. The two subunits were identified from purified MDH from Methylobacillus sp. SK-5. A dendrogram constructed by comparison of amino acid sequences of MDH u subunits suggests that MxaF from Methylobacillus sp. SK-5 belongs to a subfamily cluster of MDH u subunits from $\beta$-subgroup Proteobacteria. The subfamily cluster is separated from the other subfamily that consists of $\beta$- and $\gamma$-subgroup Proteobacteria. This study provided information on mn genes from a methylotrophic bacterium in $\beta$-subgroup Proteobacteria, which would aid to better develop a gene probe to detect one-carbon metabolizing bacteria.

• BMB Reports
• /
• v.43 no.5
• /
• pp.325-329
• /
• 2010

Protein kinase CKII (CKII), a heterotetramer composed of two catalytic ($\alpha$ or $\alpha$') subunits and two regulatory ($\beta$) subunits, plays a critical role in cell proliferation and anti-apoptosis. Recently, capsaicin was shown to trigger apoptosis. Therefore, we examined the effect of capsaicin on CKII activity. Although capsaicin induced apoptotic death in HeLa cells, CKII activity was increased in the cytosolic fraction of HeLa cells after treatment. Capsaicin did not change the expression of the $CKII{\alpha}$ and $CKII{\beta}$ proteins. Capsaicin stimulated the catalytic activity of recombinant CKII tetramer, but not the $CKII{\alpha}$ subunit. Moreover, capsaicin enhanced the autophosphorylation of $CKII{\alpha}$ and $CKII{\beta}$. Taken together, our data suggest that capsaicin stimulates the phosphotransferase activity of CKII holoenzyme by interacting with the $CKII{\beta}$ subunit.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.1
• /
• pp.17-24
• /
• 2012

We cloned and sequenced the cDNA encoding the $FSH{\beta}$ and $LH{\beta}$ subunits from the pituitary of the blacktip grouper Epinephelus fasciatus, which regulate vitellogenesis and maturation in vertebrates, to achieve stable and healthy gametes. The full-length cDNAs of $FSH{\beta}$ and $LH{\beta}$ were 571 bp and 617 bp, encoding 120 amino acid (aa) and 147 aa proteins, respectively. The deduced amino acid sequences of $FSH{\beta}$ and $LH{\beta}$ were highly homologous (68-97%) to those of other Perciformes; E. bruneus, Dicentrarchus labrax, Thunnus thynnus, and Pseudolabrus sieboldi. Phylogenetic analysis showed that the deduced $FSH{\beta}$ and $LH{\beta}$ amino acid sequences were categorized as a distinct subunit in the $GTH{\beta}$ family, and are closely related to the teleostei $FSH{\beta}$ and $LH{\beta}$, respectively. $FSH{\beta}$ and $LH{\beta}$ mRNA exhibited high abundance in the pituitary gland and low in other brain areas, but were not present in peripheral tissues, as determined by RT-PCR.

• Fisheries and Aquatic Sciences
• /
• v.18 no.4
• /
• pp.417-420
• /
• 2015

We investigated the relationship between viability and IGF-1 receptor (IGF-1R) activity in D-shaped and umbo larvae of the surf clam Spisula sachalinensis after treatment with vitrification solution (VS) or freezing. In a toxicity assay, VS1, containing 5 M dimethyl sulfoxide (DMSO), was very harmful to D-shaped and umbo larvae. However, VS2, containing 5 M ethylene glycol (EG), was not harmful to either larval stage. Although VS2 had a promising toxicity test outcome, none of the larvae survived vitrification. After immersion into VSs and freezing, IGF-1R ${\beta}$-subunits were detected in all larvae; however, tyrosine phosphorylation of intracellular ${\beta}$-subunits was detected only in the control and live groups. These results suggest that activation of IGF-1R may influence surf clam larvae viability.