Related Experiment Video
Updated: Aug 7, 2026
08:57
Myosin-Specific Adaptations of In vitro Fluorescence Microscopy-Based Motility Assays
Published on: February 4, 2021
Structural and functional differences between mouse mot-1 and mot-2 proteins that differ in two amino acids
Custer C Deocaris1, Kazuhiko Yamasaki, Sunil C Kaul
1National Institute of Advanced Industrial Science & Technology (AIST), Tsukuba, Japan.
Annals of the New York Academy of Sciences
|June 29, 2006
Summary
The heat-shock protein (HSP) mortalin has two forms, mot-1 and mot-2, with differing chaperone activities. Mot-2 exhibits higher activity, influencing cell aging and promoting malignant properties, unlike mot-1.
Area of Science:
- Molecular Biology
- Cellular Aging
- Protein Function
Background:
- Heat-shock proteins (HSPs) are crucial for organismal lifespan.
- Mortalin, a mitochondrial HSP70, is implicated in immortalization and tumorigenesis.
- Mouse mortalin exists as two alleles: mot-1 and mot-2, producing distinct proteins.
Purpose of the Study:
- To investigate the differential chaperone activities of mortalin alleles mot-1 and mot-2.
- To explore the link between mortalin's chaperone function and cellular phenotypes like senescence and malignancy.
- To propose a mechanistic explanation for the observed differences in aging phenotypes.
Main Methods:
- Overexpression of mot-1 and mot-2 in NIH 3T3 cells.
- Assessment of cellular senescence and malignant properties.
- Comparative analysis of mortalin's chaperone activity.
Main Results:
- Overexpression of mot-1 induced senescence in NIH 3T3 cells.
- Overexpression of mot-2 promoted malignant properties in NIH 3T3 cells.
- Mot-1 demonstrated significantly lower chaperone activity compared to mot-2.
Conclusions:
- The differential chaperone activities of mot-1 and mot-2 underlie their distinct effects on cellular aging and tumorigenesis.
- A 'lazy lid' hypothesis is proposed to explain the functional divergence of mortalin alleles.
- Mortalin's chaperone function is a key determinant of cellular lifespan and malignant potential.
Related Concept Videos
01:15Overview of Myosin Structure and Function
Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with their role in muscle contraction, these proteins also play a role in the intracellular transport of molecules and vesicles. There are twenty-four classes of myosins based on their domain sequence and organization. Of the twenty-four, six classes (Myosin I, Myosin II, Myosin V, Myosin VI, Myosin VII, and Myosin X) have been well characterized.
01:58Mechanical Protein Function
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
01:18Role of Myosin in Cell Migration
Myosins are multimeric motor proteins involved in various cellular processes such as migration, adhesion, and proliferation. Myosin II is the most common type in animal cells, which binds and cross-links actin filaments.
Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
Myosin II is a hexamer comprising two heavy chains with globular heads and coiled-coil tails, two regulatory light chains, and two essential light chains. The ATPase sites on the myosin heads hydrolyze ATP, and the released phosphate generates the force for contraction. It is...
01:58Mechanical Protein Functions
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
01:32Microtubule Associated Motor Proteins
Eukaryotic cells have different motor proteins for transporting various cargo within the cell. These motor proteins differ based on the filament they associate with, the direction they move within the cell, and the type of cargo they transport. Motor proteins that associate with microtubules are known as microtubule-associated motor proteins. There are two families of microtubule-associated motor proteins —Kinesins and Dyneins. Both these proteins assist in the transport of cellular cargos...
01:56Structural Protein Function
Structural proteins are a category of proteins responsible for functions ranging from cell shape and movement to providing support to major structures such as bones, cartilage, hair, and muscles. This group includes proteins such as collagen, actin, myosin, and keratin.
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to form...
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity. In bones and teeth, it mineralizes to form...