Muscle contraction molecular level

Likewise calcium is needed to couple the release of a neurotransmitter to a muscular contraction. Calcium seems also to initiate proliferation in many kinds of cells, such as muscle cells, lymphocytes, and fibroblasts. It also plays a role in phagocytosis. Those ionophores (Section 14.2) that transport calcium into cells can initiate many of these effects. Some think that, at the molecular level, calcium functions by giving ATPase access to its substrate (ATP), thus providing the energy for these various actions. 

Tliese examples of rigor at the gross anatomical level in muscle are manifestations of hydrophobic association at the molecular level they reflect the fundamental role of hydrophobic association/dissociation in the function of muscle. These occurrences of rigor in muscle do not support the view of electrostatic interactions, of direct charge-charge interactions independent of hydrophobic domains, being predominant in muscle function. These anatomical manifestations that correlate muscle contraction with hydrophobic association continue below the physiological level. 

Despite the above noted correlation of phenomena, current descriptions of molecular structure and resulting function of hemoglobin and myoglobin (as well as of muscle contraction to be addressed at the molecular level in Chapter 8) proceed without consideration of the consilient mechanism. th the consilient mechanism in mind, however, a distinctive way of looking at protein structure and function materializes. The availability of so many protein crystal structures from The Protein Data Bank and, as employed in our case, the capacity to... 

As reviewed in Chapter 7 with a focus on the issue of insolubility, extensive phenomenological correlations exist between muscle contraction and contraction by model proteins capable of inverse temperature transitions of hydrophobic association. As we proceed to examination of muscle contraction at the molecular level, a brief restatement of those correlations follows with observations of rigor at the gross anatomical level and with related physiological phenomena at the myofibril level. Each of the phenomena, seen in the elastic-contractile model proteins as an integral part of the comprehensive hydrophobic effect, reappear in the properties and behavior of muscle. More complete descriptions with references are given in Chapter 7, sections 7.2.2, and 7.2.3. 

Relaxation of the cardiac muscle requires uncoupling of the crossbridges that generated the force for the prior systolic contraction. At the level of the molecular motors (sarcomeres), this requires adenosine triphosphate (ATP) so that the molecules involved in a crossbridge interaction return to their deactivated, or off conformation. Additional ATP is required at sarcoplasmic reticulum (SR) membrane sites so that the pumps that sequester calcium back into the SR can operate. The sliding filament-based... 

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