Adenosine 5'-(gamma-thiotriphosphate): an ATP analog that should be used with caution in muscle contraction studies.
The slowly hydrolyzed ATP analog adenosine 5'-(gamma-thiotriphosphate) (ATP gamma S) has been used in many studies of the muscle motor protein myosin in order to form a stable "weak binding" state analogous to the actin-S1-ATP complex However, the results from studies using ATP gamma S do not always agree with the results of experiments using ATP. The binding of myosin subfragment-1-ATP gamma S to actin has now been studied in some detail to determine its relationship to the actin-S1-ATP state. The binding of myosin subfragment-1-ATP gamma S to actin-troponin-tropomyosin is similar in affinity to the binding of myosin subfragment-1-ATP. Like myosin subfragment-1-ATP, the binding is not Ca(2+)-dependent, and most importantly, myosin subfragment-1-ATP gamma S does not stabilize the active configuration of actin-troponin-tropomyosin. Thus, myosin subfragment-1-ATP gamma S is an analog of myosin subfragment-1-ATP but must be used with caution for two reasons: (1) The binding of ATP gamma S to regulated actomyosin subfragment-1 is Ca(2+)-sensitive, and errors can be made in the interpretation of results if proteins are not fully saturated with nucleotide and a mixture of weak and strong binding states is present. (2) At the high concentrations of myosin subfragment-1 used in some experiments, significant amounts of ADP may form.(ABSTRACT TRUNCATED AT 250 WORDS)
East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA.
A M
AM
Resetar
J M
JM
Chalovich
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D016477:Artifacts; D002118:Calcium / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D015879:Myosin Subfragments / Q000378:metabolism*; D011817:Rabbits; D013997:Time Factors; D014335:Tropomyosin / Q000378:metabolism; D014336:Troponin / Q000378:metabolism
D000199:Actins; D015879:Myosin Subfragments; D014335:Tropomyosin; D014336:Troponin; C022571:adenosine 5'-O-(3-thiotriphosphate); D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D002118:Calcium