Biomaterial Database

Orientation of paramagnetic probes attached to gizzard regulatory light chain bound to myosin heads in rabbit skeletal muscle. 1996

L Zhao, and J Gollub, and R Cooke

Department of Biochemistry & Biophysics, University of California, San Francisco 94143-0448, USA.

The orientation of the myosin neck was monitored using electron paramagnetic resonance (EPR) spectroscopy. Gizzard regulatory light chain was labeled with a nitroxide spin probe and exchanged for the native subunit, located in the myosin neck, in rabbit psoas muscle fibers. The EPR spectra of rigor fibers indicated a substantial degree of probe immobilization and showed a strong dependence on the orientation of the fiber axis relative to the magnetic field, indicating that the neck was ordered in this state. Spectra of relaxed fibers at 24 degrees C showed that the neck was disordered, but the spectra of relaxed fibers at 4 degrees C indicated that the neck was partially ordered. Active fibers at the two temperatures produced spectra identical to relaxed fibers, indicating that no novel angles could be seen in the neck during the powerstroke. Proteolytic fragments of myosin, S1 and HMM, were exchanged with labeled light chains and bound to thin filaments in unlabeled fibers. The distribution of probe orientations for HMM was identical to that of labeled rigor fibers, while S1 showed a slightly different distribution, suggesting that the neck is distorted (by a few degrees) by the interactions of the two heads of myosin when bound to actin.

UI	MeSH Term	Description	Entries
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009130	Muscle, Smooth	Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)	Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002645	Chickens	Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.	Gallus gallus,Gallus domesticus,Gallus gallus domesticus,Chicken
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D005895	Gizzard, Avian	The posterior portion of the avian stomach located between the PROVENTRICULUS and INTESTINE. It consists of a thick muscular wall and small stones (gastroliths) that function to mechanically grind SEEDS and other ingested objects.	Gizzard,Ventriculus,Avian Gizzard,Avian Gizzards,Gizzards,Gizzards, Avian
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013113	Spin Labels	Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)	Spin Label,Label, Spin,Labels, Spin
D014336	Troponin	One of the minor protein components of skeletal and cardiac muscles. It functions as the calcium-binding component in a complex with BETA-TROPOMYOSIN; ACTIN; and MYOSIN and confers calcium sensitivity to the cross-linked actin and myosin filaments. Troponin itself is a complex of three regulatory proteins (TROPONIN C; TROPONIN I; and TROPONIN T).	Troponin Complex,Troponins
D015879	Myosin Subfragments	Parts of the myosin molecule resulting from cleavage by proteolytic enzymes (PAPAIN; TRYPSIN; or CHYMOTRYPSIN) at well-localized regions. Study of these isolated fragments helps to delineate the functional roles of different parts of myosin. Two of the most common subfragments are myosin S-1 and myosin S-2. S-1 contains the heads of the heavy chains plus the light chains and S-2 contains part of the double-stranded, alpha-helical, heavy chain tail (myosin rod).	Actomyosin Subfragments,Meromyosin Subfragments,Myosin Rod,Myosin S-1,Myosin S-2,ATPase, Actin-S1,Actin S1 ATPase,Actoheavy Meromyosin,Actomyosin Subfragment 1 ATPase,H-Meromyosin,Heavy Meromyosin,Heavy Meromyosin Subfragment-1,Heavy Meromyosin Subfragment-2,Light Meromyosin,Myosin Subfragment-1,Myosin Subfragment-2,ATPase, Actin S1,Actin-S1 ATPase,H Meromyosin,Heavy Meromyosin Subfragment 1,Heavy Meromyosin Subfragment 2,Meromyosin Subfragment-1, Heavy,Meromyosin Subfragment-2, Heavy,Meromyosin, Actoheavy,Meromyosin, Heavy,Meromyosin, Light,Myosin S 1,Myosin S 2,Myosin Subfragment 1,Myosin Subfragment 2,Subfragment-1, Heavy Meromyosin,Subfragment-1, Myosin,Subfragment-2, Heavy Meromyosin,Subfragment-2, Myosin,Subfragments, Actomyosin,Subfragments, Meromyosin,Subfragments, Myosin