Identification of the γ-subunit interaction sites in the retinal cyclic-GMP phosphodiesterase β-subunit

In a previous report, we found that mutations at the mitochondrial genome integrity locus, MGI1, can convert Kluyveromyces lactis into a petite-positive yeast. In this report, we describe the isolation of the MGI1 gene and show that it encodes the β-subunit of the mitochondrial F1-ATPase. The site of mutation in four independently isolated mgi1 alleles is at Arg435, which has changed to Gly in three cases and Ile in the fourth isolate. Disruption of MGI1 does not lead to the production of mitochondrial genome deletion mutants, indicating that an assembled F1 complex is needed for the “gain-of-function” phenotype found in mgi1 point mutants. The location of Arg435 in the β-subunit, as deduced from the three-dimensional structure of the bovine F1-ATPase, together with mutational sites in the previously identified mgi2 and mgi5 alleles, suggests that interaction of the β- and α- (MGI2) subunits with the γ-subunit (MGI5) is likely to be affected by the mutations.

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Neural regulation of the formation of skeletal muscle phosphorylase kinase holoenzyme in adult and developing rat muscle

Biochemical Journal ◽

10.1042/bj3250793 ◽

1997 ◽

Vol 325 (3) ◽

pp. 793-800 ◽

Cited By ~ 2

Author(s):

Dean C. NG ◽

Richard C. CARLSEN ◽

Donal A. WALSH

Keyword(s):

Skeletal Muscle ◽

Muscle Development ◽

Rapid Decline ◽

Phosphorylase Kinase ◽

Β Subunit ◽

Subunit Protein ◽

Subunit Mrna ◽

Γ Subunit ◽

Muscle Phosphorylase ◽

Denervated Muscles

Neural influences on the co-ordination of expression of the multiple subunits of skeletal muscle phosphorylase kinase and their assembly to form the holoenzyme complex, α4β4γ4δ4, have been examined during denervation and re-innervation of adult skeletal muscle and during neonatal muscle development. Denervation of the tibialis anterior and extensor digitorum longus muscles of the rat hindlimb was associated with a rapid decline in the mRNA for the γ subunit, and an abrupt decrease in γ-subunit protein. The levels of the α- and β-subunit proteins in the denervated muscles also declined rapidly, their time course of reduction being similar to that for the γ-subunit protein, but they did not decrease to the same extent. In contrast with the rapid decline in γ-subunit mRNA upon denervation, α- and β-subunit mRNAs stayed at control innervated levels for approx. 8–10 days, but then decreased rapidly. Their decline coincided very closely with the onset of re-innervation. Re-innervation of the denervated muscles, which occurs rapidly and uniformly after the sciatic nerve crush injury, produced an eventual slow and prolonged recovery of the mRNA for all three subunits and parallel increases in each of the subunit proteins. A similar co-ordinated increase of both subunit mRNA and subunit proteins of the phosphorylase kinase holoenzyme was observed during neonatal muscle development, during the period when the muscles were attaining their adult pattern of motor activity. The phosphorylase kinase holoenzyme remains in a non-activated form during all of these physiological changes, as is compatible with the presence of the full complement of the regulatory subunits. These data are consistent with a model whereby the transcriptional and translational expression of phosphorylase kinase γ subunit occurs only with concomitant expression of the α and β subunits. This would ensure that free and unregulated, activated γ subunit alone, which would give rise to unregulated glycogenolysis, is not produced. The data also suggest that control of phosphorylase kinase subunit expression and the formation of the holoenzyme in skeletal muscle is provided by the motor nerve, probably through imposed levels or patterns of muscle activity.

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Differential Regulation of the Epithelial Sodium Channel (ENaC) in Rat Kidney, Lung and Distal Colon in Response to Aldosterone.

Hypertension ◽

10.1161/hyp.36.suppl_1.724 ◽

2000 ◽

Vol 36 (suppl_1) ◽

pp. 724-724

Author(s):

Shyama M E Masilamani ◽

Gheun-Ho Kim ◽

Mark A Knepper

Keyword(s):

Sodium Channel ◽

Epithelial Sodium Channel ◽

Distal Colon ◽

Β Subunit ◽

Dietary Salt ◽

Α Subunit ◽

Salt Restriction ◽

Γ Subunit ◽

Dietary Salt Restriction ◽

Epithelial Sodium Channel Enac

P170 The mineralocorticoid hormone, aldosterone increases renal tubule Na absorption via increases in the protein abundances of the α-subunit of the epithelial sodium channel (ENaC) and the 70 kDa form of the γ- subunit of ENaC (JCI 104:R19-R23). This study assesses the affect of dietary salt restriction on the regulation of the epithelial sodium channel (ENaC) in the lung and distal colon, in addition to kidney, using semiquantitative immunoblotting. Rats were placed initially on either a control Na intake (0.02 meq/day), or a low Na intake (0.2 meq/day) for 10 days. The low salt treated rats demonstrated an increase in plasma aldosterone levels at day 10 (control = 0.78 + 0.32 nM; Na restricted = 3.50 + 1.30 nM). In kidney homogenates, there were marked increases in the band density of the α-subunit of ENaC (286 % of control) and the 70 kDa form of γ-subunit of ENaC (262 % of control), but no increase in the abundance of the β-subunit of ENaC. In lung homogenates, there was no significant change in the band densities of the α, β, or γ subunits of ENaC. In distal colon, there was an increase in the band density of the β-subunit of ENaC (311 % of control) and an increase in both the 85 kDa (2355% of control) and 70 kDa (843 % of control) form of the γ subunit of ENaC in response to dietary Na restriction. However, there was no significant difference in the band density of the α-subunit of ENaC. These findings demonstrate tissue specific regulation of the three subunits of ENaC in response to dietary salt restriction.

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Interaction Sites of the COOH-terminal Region of the γ Subunit of cGMP Phosphodiesterase with the GTP-bound α Subunit of Transducin

Journal of Biological Chemistry ◽

10.1074/jbc.271.43.26900 ◽

1996 ◽

Vol 271 (43) ◽

pp. 26900-26907 ◽

Cited By ~ 23

Author(s):

Yu Liu ◽

Vadim Y. Arshavsky ◽

Arnold E. Ruoho

Keyword(s):

Terminal Region ◽

Α Subunit ◽

Cgmp Phosphodiesterase ◽

Interaction Sites ◽

Γ Subunit

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The α1-β-Subunit Interaction That Modulates Calcium Channel Activity Is Reversible and Requires a Competent α-Interaction Domain

Journal of Biological Chemistry ◽

10.1074/jbc.m605930200 ◽

2006 ◽

Vol 281 (34) ◽

pp. 24104-24110 ◽

Cited By ~ 38

Author(s):

Patricia Hidalgo ◽

Giovanni Gonzalez-Gutierrez ◽

Jennie Garcia-Olivares ◽

Alan Neely

Keyword(s):

Calcium Channel ◽

Β Subunit ◽

Channel Activity ◽

Subunit Interaction ◽

Interaction Domain

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Follicle-stimulating hormone-induced prostaglandin E formation in isolated rat ovarian theca

Journal of Endocrinology ◽

10.1677/joe.0.0970043 ◽

1983 ◽

Vol 97 (1) ◽

pp. 43-49 ◽

Cited By ~ 4

Author(s):

U. Zor ◽

B. Strulovici ◽

R. Braw ◽

H. R. Lindner ◽

A. Tsafriri

Keyword(s):

Cyclic Amp ◽

Cyclic Gmp ◽

Follicle Stimulating Hormone ◽

Fold Increase ◽

Prostaglandin E ◽

Β Subunit ◽

Biochemical Effects ◽

Isolated Rat ◽

Stimulating Hormone

The aim of this study was to search for direct biochemical effects of highly purified FSH on isolated ovarian follicular theca in vitro. Granulosa cells (GC; approximately 1 × 105 cells per follicle) were flushed from isolated follicles of pro-oestrous rats. The remaining theca layer and the isolated GC were incubated with highly purified ovine FSH. Prostaglandin E (PGE) accumulation was measured by radioimmunoassay. Follicle-stimulating hormone induced a 15-fold increase in PGE accumulation over the basal level in the follicular theca, the stimulated rate exceeding threefold that observed in the GC fraction derived from the same follicle. Follicle-stimulating hormone caused no significant increase in cyclic AMP level or steroidogenesis in the theca layer, but was active on these parameters in the GC. In contrast, LH increased the accumulation of cyclic AMP, progesterone and testosterone, as well as of PGE, in follicular theca. Exogenous 8-bromo cyclic AMP or cyclic GMP also stimulated PGE production in follicular theca or GC, but FSH was without any effect on the level of endogenous cyclic GMP in GC or follicular theca. Antibodies to FSH prevented the effect of FSH (but not that of LH) on PGE formation by follicular theca and GC, while antibodies to the β-subunit of LH blocked the effect of LH but not of FSH. We conclude that highly purified FSH has a stimulatory effect on PGE formation by the follicular theca.

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Cloning and sequencing of the γ-subunit of retinal cyclic-GMP phosphodiesterase from rd mouse

Experimental Eye Research ◽

10.1016/0014-4835(89)90069-9 ◽

1989 ◽

Vol 48 (6) ◽

pp. 863-872 ◽

Cited By ~ 6

Author(s):

Narendra Tuteja ◽

Renu Tuteja ◽

Debora B. Farber

Keyword(s):

Cyclic Gmp ◽

Cloning And Sequencing ◽

Γ Subunit

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The γ-subunit of ENaC is more important for channel surface expression than the β-subunit

AJP Cell Physiology ◽

10.1152/ajpcell.00385.2002 ◽

2003 ◽

Vol 284 (2) ◽

pp. C447-C456 ◽

Cited By ~ 46

Author(s):

Angelos-Aristeidis Konstas ◽

Christoph Korbmacher

Keyword(s):

Cell Surface ◽

Sodium Current ◽

Critical Role ◽

Surface Expression ◽

Xenopus Laevis Oocytes ◽

Β Subunit ◽

Extracellular Loops ◽

Γ Subunit ◽

Electrolyte Homeostasis ◽

Epithelial Sodium Channel Enac

The amiloride-sensitive epithelial sodium channel (ENaC) plays a critical role in fluid and electrolyte homeostasis and is composed of three homologous subunits: α, β, and γ. Only heteromultimeric channels made of αβγENaC are efficiently expressed at the cell surface, resulting in maximally amiloride-sensitive currents. To study the relative importance of various regions of the β- and γ-subunits for the expression of functional ENaC channels at the cell surface, we constructed hemagglutinin (HA)-tagged β-γ-chimeric subunits composed of β- and γ-subunit regions and coexpressed them with HA-tagged αβ- and αγ-subunits in Xenopus laevis oocytes. The whole cell amiloride-sensitive sodium current (Δ I ami) and surface expression of channels were assessed in parallel using the two-electrode voltage-clamp technique and a chemiluminescence assay. Because coexpression of αγENaC resulted in larger Δ I ami and surface expression compared with coexpression of αβENaC, we hypothesized that the γ-subunit is more important for ENaC trafficking than the β-subunit. Using chimeras, we demonstrated that channel activity is largely preserved when the highly conserved second cysteine rich domains (CRD2) of the β- and γ-subunits are exchanged. In contrast, exchanging the whole extracellular loops of the β- and the γ-subunits largely reduced ENaC currents and ENaC expression in the membrane. This indicates that there is limited interchangeability between molecular regions of the two subunits. Interestingly, our chimera studies demonstrated that the intracellular termini and the two transmembrane domains of γENaC are more important for the expression of functional channels at the cell surface than the corresponding regions of βENaC.

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