Related Experiment Video

Updated: Oct 16, 2026

Monitoring ER/SR Calcium Release with the Targeted Ca2+ Sensor CatchER+
12:30

Monitoring ER/SR Calcium Release with the Targeted Ca2+ Sensor CatchER+

Published on: May 19, 2017

Identification of a 97-kDa mastoparan-binding protein involving in Ca(2+) release from skeletal muscle sarcoplasmic

Y Hirata1, N Nakahata, Y Ohizumi

  • 1Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-Ku, Sendai, Japan.

Molecular Pharmacology
|May 29, 2000
PubMed

Insights

Mastoparan (MP) triggers calcium release from the sarcoplasmic reticulum by interacting with a distinct 97-kDa protein, not the ryanodine receptor. This finding suggests a novel mechanism in skeletal muscle excitation-contraction coupling.

Area of Science:

  • Molecular Biology
  • Muscle Physiology
  • Biochemistry

Background:

  • Sarcoplasmic reticulum Ca(2+) release is critical for skeletal muscle excitation-contraction coupling.
  • Ryanodine receptors are primary regulators of Ca(2+) release, but other modulators may exist.
  • Mastoparan (MP), a wasp venom peptide, is known to affect cellular processes.

Purpose of the Study:

  • To investigate the mechanism by which Mastoparan (MP) induces Ca(2+) release from the sarcoplasmic reticulum.
  • To identify the specific protein target of MP involved in Ca(2+) release.
  • To elucidate the role of this interaction in skeletal muscle function.

Main Methods:

  • Used radiolabeled Mastoparan ([Tyr(3)]MP and (125)I-[Tyr(3)]MP) to study binding and Ca(2+) release from isolated sarcoplasmic reticulum fractions.
  • Investigated the effects of MP and caffeine on (45)Ca(2+) release and [(3)H]ryanodine binding.
  • Utilized specific antibodies and immunoprecipitation to identify MP-binding proteins.

Main Results:

  • MP induced Ca(2+) release from sarcoplasmic reticulum, distinct from caffeine-induced release, and enhanced ryanodine binding.
  • Radiolabeled MP specifically bound to a 97-kDa protein, not the ryanodine receptor, triadin, or Ca(2+)-pump.
  • The 97-kDa MP-binding protein's interaction with MP was independent of caffeine binding sites.

Conclusions:

  • Mastoparan (MP) interacts with a novel 97-kDa protein in the sarcoplasmic reticulum, mediating Ca(2+) release.
  • This MP-binding protein represents a potential new player in skeletal muscle excitation-contraction coupling.
  • Further research is warranted to fully characterize this protein and its physiological role.

More Related Videos

Purification of the Sarco-Endoplasmic Reticulum Ca2+-ATPase from Rabbit Muscle08:37

Purification of the Sarco-Endoplasmic Reticulum Ca2+-ATPase from Rabbit Muscle

Published on: March 21, 2025

Isolation of Human Myoblasts, Assessment of Myogenic Differentiation, and Store-operated Calcium Entry Measurement10:45

Isolation of Human Myoblasts, Assessment of Myogenic Differentiation, and Store-operated Calcium Entry Measurement

Published on: July 26, 2017

Related Concept Videos

Overview of Skeletal Muscle01:15

Overview of Skeletal Muscle

Skeletal muscles are composed of a bundle of muscle fibers and are attached to bones through tendons. Each skeletal muscle fiber is a single muscle cell. The sarcolemma, the plasma membrane of a skeletal muscle cell, consists of a lipid bilayer and glycocalyx that supports muscle fibers. The sarcolemma extends into the muscle cells to form tubular structures called transverse or T-tubules. Each side of the T-tubules consists of a membrane-bound structure called the sarcoplasmic reticulum,...
Calmodulin-dependent Signaling01:16

Calmodulin-dependent Signaling

Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Sarcomere01:08

The Sarcomere

A sarcomere is a microscopic segment repeating in a myofibril. The sarcomere fundamentally consists of two main myofilaments: thick filaments called myosin and thin filaments called actin. These filaments interact by sliding past each other in response to stimulus. In addition to myosin and actin, several other proteins, such as tropomyosin, troponin, titin, nebulin, myomesin, α-actinin, and dystrophin, play crucial roles in regulating, structuring, and functioning of the sarcomere.
Each myosin...
Relaxation of Skeletal Muscles01:29

Relaxation of Skeletal Muscles

The period of muscle contraction primarily influences the duration of stimulation at the neuromuscular junction (NMJ), the presence of free calcium ions in the sarcoplasm, and the availability of energy or ATP to support contractions.
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Cross-bridge Cycle01:26

Cross-bridge Cycle

As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
Overview of Secretory Vesicles01:33

Overview of Secretory Vesicles

Secretory vesicles, also known as dense core vesicles (DCVs), are membrane-bound vesicles that transport secretory proteins, such as hormones or neurotransmitters. Regulated secretory vesicles transport proteins from the trans-Golgi network to the exterior of the cell. Proteins present in regulated secretory vesicles are required to be rapidly exocytosed in large amounts upon a specific stimulus.
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...