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Gene Review

KCNMA1  -  potassium large conductance calcium...

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Disease relevance of KCNMA1

  • The effect of UTP on Maxi-K channel activity and current amplitude was blocked by pertussis toxin and by phorbol 12-myristate 13-acetate (PMA), but was not modified by okadaic acid, or by inhibitors of protein kinase C (PKC) [1].

High impact information on KCNMA1

  • The widespread distribution of the BK channel class suggests that the significance of its modulation by opioids could also extend beyond the adrenal gland [2].
  • This receptor has previously been shown to be an integral component of the high-conductance Ca2+-activated K+ (Maxi-K) channel in these smooth muscles [3].
  • Thus, phosphorylation/dephosphorylation by PKC determines whether the BK channel is stimulated by cGK or cAK [4].
  • The difference in size of the alpha subunit as expressed in these membranes and the purified preparations is due to a highly reproducible proteolytic decay that occurs mostly at an advanced stage of the maxi-K channel purification [5].
  • Amino acid sequence information obtained from these fragments reveals the existence of very high sequence homology with the recently cloned mSlo maxi-K channel (Butler, A., Tsunoda, S., McCobb, D. P., Wei, A., and Salkoff, L. (1993) Science 261, 221-224) [6].

Biological context of KCNMA1

  • Patch-clamp electrophysiology was used to investigate coupling between the mu receptor and BK channel, leading to rather surprising results [7].
  • We concluded that the synthetic polycations had at least two sites of action; one is the delayed rectifier K(+) channel that is responsible for the membrane depolarization that increases Ca(2+) influx, and the other is the maxi-K channel the suppression of which inhibits muscle relaxation [8].
  • We conclude that ANP via the activation of the ANP A receptor alters K+ homeostasis through a Ca(2+)-activatable K(+)-conductive pathway likely to be the maxi-K channel [9].

Anatomical context of KCNMA1


Associations of KCNMA1 with chemical compounds


Other interactions of KCNMA1

  • These results suggest that the BAMCC BK channel is not coupled to the mu receptor via a GTP-dependent mechanism, whereas in the same cells the dopamine D2 receptor modulates BK channel activity in a conventional GTP-dependent manner [7].


  1. Mobilization of intracellular calcium in cultured vascular smooth muscle cells by uridine triphosphate and the calcium ionophore A23187. Sanchez-Fernandez, M., Katz, G.M., Suarez-Kurtz, G., Kaczorowski, G.J., Reuben, J.P. J. Membr. Biol. (1993) [Pubmed]
  2. Opioid peptide modulation of Ca(2+)-dependent K+ and voltage-activated Ca2+ currents in bovine adrenal chromaffin cells. Twitchell, W.A., Rane, S.G. Neuron (1993) [Pubmed]
  3. Functional unit size of the charybdotoxin receptor in smooth muscle. Garcia-Calvo, M., Knaus, H.G., Garcia, M.L., Kaczorowski, G.J., Kempner, E.S. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
  4. A molecular switch for specific stimulation of the BKCa channel by cGMP and cAMP kinase. Zhou, X.B., Arntz, C., Kamm, S., Motejlek, K., Sausbier, U., Wang, G.X., Ruth, P., Korth, M. J. Biol. Chem. (2001) [Pubmed]
  5. Characterization of tissue-expressed alpha subunits of the high conductance Ca(2+)-activated K+ channel. Knaus, H.G., Eberhart, A., Koch, R.O., Munujos, P., Schmalhofer, W.A., Warmke, J.W., Kaczorowski, G.J., Garcia, M.L. J. Biol. Chem. (1995) [Pubmed]
  6. Subunit composition of the high conductance calcium-activated potassium channel from smooth muscle, a representative of the mSlo and slowpoke family of potassium channels. Knaus, H.G., Garcia-Calvo, M., Kaczorowski, G.J., Garcia, M.L. J. Biol. Chem. (1994) [Pubmed]
  7. Nucleotide-independent modulation of Ca(2+)-dependent K+ channel current by a mu-type opioid receptor. Twitchell, W.A., Rane, S.G. Mol. Pharmacol. (1994) [Pubmed]
  8. Suppression of maxi-K channel and membrane depolarization by synthetic polycations in single tracheal myocytes. Oshiro, T., Sasaki, T., Nara, M., Tamada, T., Shimura, S., Maruyama, Y., Shirato, K. Am. J. Respir. Cell Mol. Biol. (2000) [Pubmed]
  9. Atrial natriuretic peptide enhances activity of potassium conductance in adrenal glomerulosa cells. Ganz, M.B., Nee, J.J., Isales, C.M., Barrett, P.Q. Am. J. Physiol. (1994) [Pubmed]
  10. Effect of high hydrostatic pressure on the BK channel in bovine chromaffin cells. Macdonald, A.G. Biophys. J. (1997) [Pubmed]
  11. Electrostatic mutations in iberiotoxin as a unique tool for probing the electrostatic structure of the maxi-K channel outer vestibule. Mullmann, T.J., Munujos, P., Garcia, M.L., Giangiacomo, K.M. Biochemistry (1999) [Pubmed]
  12. Characterization of the solubilized charybdotoxin receptor from bovine aortic smooth muscle. Garcia-Calvo, M., Vázquez, J., Smith, M., Kaczorowski, G.J., Garcia, M.L. Biochemistry (1991) [Pubmed]
  13. Inhibitory mechanism of papaverine on carbachol-induced contraction in bovine trachea. Kaneda, T., Takeuchi, Y., Matsui, H., Shimizu, K., Urakawa, N., Nakajyo, S. J. Pharmacol. Sci. (2005) [Pubmed]
  14. Mechanism of maxi-K channel activation by dehydrosoyasaponin-I. Giangiacomo, K.M., Kamassah, A., Harris, G., McManus, O.B. J. Gen. Physiol. (1998) [Pubmed]
  15. Stimulatory regulation of the large-conductance, calcium-activated potassium channel by G proteins in bovine adrenal chromaffin cells. Walsh, K.B., Wilson, S.P., Long, K.J., Lemon, S.C. Mol. Pharmacol. (1996) [Pubmed]
  16. Potent inhibition of the aortic smooth muscle maxi-K channel by clinical doses of ethanol. Walters, F.S., Covarrubias, M., Ellingson, J.S. Am. J. Physiol., Cell Physiol. (2000) [Pubmed]
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