Abstract
Helothermine, a protein from the venom of the Mexican beaded lizard (Heloderma horridum horridum), was found to inhibit [3H]ryanodine binding to cardiac and skeletal sarcoplasmic reticulum, to block cardiac and skeletal ryanodine receptor channels incorporated into planar bilayers, and to block Ca(2+)-induced Ca2+ release triggered by photolysis of nitr-5 in saponin-permeabilized trabeculae from rat ventricle. Cloning of the helothermine cDNA revealed that the protein is composed of 223 amino acids with a molecular mass of 25,376 daltons, and apparently is stabilized by eight disulfide bridges. The peptide sequence showed significant homology with a family of cysteine-rich secretory proteins found in the male genital tract and in salivary glands. The interaction of helothermine and ryanodine receptors should serve to define functional domains within the channel structure involved in the control of Ca2+ release from sarcoplasmic reticulum.
Publication types
-
Comparative Study
-
Research Support, Non-U.S. Gov't
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Amino Acid Sequence
-
Animals
-
Base Sequence
-
Binding, Competitive
-
Calcium Channel Blockers / chemistry*
-
Calcium Channel Blockers / pharmacology
-
Calcium Channels / drug effects
-
Calcium Channels / physiology*
-
Cloning, Molecular
-
DNA, Complementary
-
Lipid Bilayers
-
Lizards
-
Membrane Potentials / drug effects
-
Microsomes / metabolism
-
Molecular Sequence Data
-
Muscle Proteins / drug effects
-
Muscle Proteins / physiology*
-
Muscle, Skeletal / metabolism
-
Myocardium / metabolism
-
Oligonucleotide Probes
-
Peptide Biosynthesis
-
Peptides / chemistry*
-
Peptides / pharmacology*
-
Rabbits
-
Recombinant Proteins / biosynthesis
-
Recombinant Proteins / chemistry
-
Recombinant Proteins / pharmacology
-
Ryanodine / metabolism
-
Ryanodine Receptor Calcium Release Channel
-
Sarcoplasmic Reticulum / metabolism
-
Sequence Homology, Amino Acid
-
Swine
-
Toxins, Biological / chemistry
-
Toxins, Biological / pharmacology
Substances
-
Calcium Channel Blockers
-
Calcium Channels
-
DNA, Complementary
-
Lipid Bilayers
-
Muscle Proteins
-
Oligonucleotide Probes
-
Peptides
-
Recombinant Proteins
-
Ryanodine Receptor Calcium Release Channel
-
Toxins, Biological
-
helothermine
-
Ryanodine