Identification and Characterization of Three Calmodulin Binding Sites of the Skeletal Muscle Ryanodine Receptor

Biochemistry ◽  
1994 ◽  
Vol 33 (31) ◽  
pp. 9078-9084 ◽  
Author(s):  
Paola Menegazzi ◽  
Fulvia Larini ◽  
Susan Treves ◽  
Remo Guerrini ◽  
Manfredo Quadroni ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Binding Sites ◽  
Calmodulin Binding ◽  
Identification And Characterization

scholarly journals Suramin and the suramin analogue NF307 discriminate among calmodulin-binding sites

2001 ◽  
Vol 355 (3) ◽  
pp. 827-833 ◽  
Author(s):  
Markus KLINGER ◽  
Elisa BOFILL-CARDONA ◽  
Bernd MAYER ◽  
Christian NANOFF ◽  
Michael FREISSMUTH ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Binding Sites ◽  
Metabotropic Glutamate Receptor ◽  
Target Proteins ◽  
Porcine Brain ◽  
Metabotropic Glutamate ◽  
Calmodulin Binding ◽  
Brain Membranes ◽  
Bacterial Lysates

Calmodulin-binding sites on target proteins show considerable variation in primary sequence; hence compounds that block the access of calmodulin to these binding sites may be more selective than compounds that inactivate calmodulin. Suramin and its analogue NF307 inhibit the interaction of calmodulin with the ryanodine receptor. We have investigated whether inhibition of calmodulin binding to target proteins is a general property of these compounds. Suramin inhibited binding of [125I]calmodulin to porcine brain membranes and to sarcoplasmic reticulum from skeletal muscle (IC50 = 4.9±1.2µM and 19.9±1.8µM, respectively) and blocked the cross-linking of [125I]calmodulin to some, but not all, target proteins in brain membranes by [125I]calmodulin. Four calmodulin-binding proteins were purified [ryanodine receptor-1 (RyR1) from rabbit skeletal muscle, neuronal NO synthase (nNOS) from Sf9 cells, G-protein βγ dimers (Gβγ) from porcine brain and a glutathione S-transferase-fusion protein comprising the C-terminal calmodulin-binding domain of the metabotropic glutamate receptor 7A (GST-CmGluR7A) from bacterial lysates]. Three of the proteins employed (Gβγ, GST-CmGluR7A and RyR1) display a comparable affinity for calmodulin (in the range of 50–70nM). Nevertheless, suramin and NF307 only blocked the binding of Gβγ and RyR1 to calmodulin–Sepharose. In contrast, the association of GST-CmGluR7A and nNOS was not impaired, whereas excess calmodulin uniformly displaced all proteins from the matrix. Thus suramin and NF307 are prototypes of a new class of calmodulin antagonists that do not interact directly with calmodulin but with calmodulin-recognition sites. In addition, these compounds discriminate among calmodulin-binding motifs.

scholarly journals Localization of calmodulin binding sites on the ryanodine receptor from skeletal muscle by electron microscopy

1994 ◽  
Vol 67 (6) ◽  
pp. 2286-2295 ◽  
Author(s):  
T. Wagenknecht ◽  
J. Berkowitz ◽  
R. Grassucci ◽  
A.P. Timerman ◽  
S. Fleischer
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Binding Sites ◽  
Calmodulin Binding

scholarly journals Identification and characterization of carbapenem binding sites within the RND-transporter AcrB

2019 ◽  
Vol 1861 (1) ◽  
pp. 62-74 ◽  
Author(s):  
Alessio Atzori ◽  
Viveka N. Malviya ◽  
Giuliano Malloci ◽  
Jürg Dreier ◽  
Klaas M. Pos ◽  
...  
Keyword(s):  
Binding Sites ◽  
Rnd Transporter ◽  
Identification And Characterization

Identification and characterization of a corticotrophin-releasing hormone receptor in human placenta

1995 ◽  
Vol 133 (5) ◽  
pp. 591-597 ◽  
Author(s):  
Vicki L Clifton ◽  
Phillip C Owens ◽  
Phillip J Robinson ◽  
Roger Smith
Keyword(s):  
Human Placenta ◽  
Binding Sites ◽  
Hormone Receptor ◽  
Human Myometrium ◽  
Scatchard Analysis ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Identification And Characterization ◽  
Crh Receptors

Clifton VL, Owens PC, Robinson PJ, Smith R. Identification and characterization of a corticotrophinreleasing hormone receptor in human placenta. Eur J Endocrinol 1995;133:591–7. ISSN 0804–4643 Corticotrophin-releasing hormone (CRH) causes vasodilatation in the human fetal–placental circulation and has paracrine actions in placental tissue, suggesting that CRH receptors may be present in the human placenta. We have now identified and characterized placental CRH binding sites and compared them to those described previously in human myometrium and rat pituitary. Radiolabelled ovine CRH binding to placental membranes was pH-, time-, temperature- and divalent cation-dependent and was reversible in the presence of 1 μmol/l unlabelled ovine CRH. Scatchard analysis of placentae delivered vaginally or by elective caesarean section revealed dissociation constants (Kd) of 214.5 ± 84 pmol/l (N = 8) and 45.4 ± 23.9 pmol/l (N = 9), respectively. The Kd for caesarean placental binding sites was similar to that of human myometrium (59.6 pmol/l, N = 3) and rat pituitary (82.5 pmol/l, N = 3) receptors. However, in vaginally delivered placentae the CRH binding sites had a much lower affinity (p < 0.05). The receptor densities (Bmax) of vaginally delivered and caesarean-delivered placentae were 28.6 ± 9.6 and 6.1 ± 2.8 fmol/mg, respectively (p < 0.05). Chemical cross-linking studies using disuccinimidyl suberate indicated that the molecular weight of the CRH receptor in the placenta and rat pituitary is 75 kD. We conclude that there is a high-affinity population of CRH binding sites in the human placenta that are physicochemically similar to pituitary and myometrial CRH receptors. The CRH receptor properties in the placenta change in response to labour, when CRH levels in maternal blood are highest, suggesting that placental CRH may regulate its receptor. R Smith, Endocrinology Unit, John Hunter Hospital, Locked Bag 1, Hunter Regional Mail Centre, Newcastle, NSW 2310, Australia

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