Amino-terminal domain and

They are so called because of a conserved cysteine loop in their extracellular domain. Structural and functionnal evidence support the view that these allosteric proteins are heteropen-tameric oligomers each subunit made up of an extracellular amino-terminal domain and four transmembrane segments. This superfamilly includes ... 

Dublet, B., Oh, S., Sugrue, S.P. et at. (1989). The structure of avian typeXII collagen- a-l(XII) chains contain 190 kDa non-triple helical amino-terminal domains and form homotrimeric molecules. ]. Biol. Chem., 264, 13150-6. 

In what follows, we extend these insights in two significant ways. One way recognizes that the narrow cleft not only splits the 50-kDa segment in the direction of the binding site with actin, but also that the narrow cleft is directed toward the junction between the amino-terminal domain and the head of the lever arm to, in our view, effect the conformational change that results in the powerstroke. Our second extension is in the nature of the force emanating from the y-phosphate in both... 

Hydrolysis of ATP to release the y-phosphate as Pi that leaves the structure, therefore, has two consequences. Strong hydrophobic association is re-established between the cross-bridge and the actin binding site, and strong hydro-phobic association is re-established between the amino-terminal domain and the head of the lever arm to provide the powerstroke. This perspective resides at the heart of the proposed contribution of the hydrophobic consilient mechanism to function of the myosin II motor. It is considered further below and most directly in section 8.S.4.7. 

Figure 8.58. Stereo view in space-filling representation of scallop cross-bridge (SI) showing narrow clefts emanating in two directions from the nucleotide binding site, located by the white circle. One cleft runs upward to the actin binding site, and the second direction is toward the hydrophobic association between the amino-terminal domain and the head of the lever arm in A to effect the hydrophobic...

X-ray studies of the 3D structure of lipase confirmed the existence of only one domain, except in pancreatic lipases where there were two distinct domains a large N-terminal domain (amino-terminal domain) and a smaller C-terminal domain. The large N-terminal domain is a typical hydrolase that contains an active site with a catalytic triad formed by Ser, Asp, and His (van Tilbeurgh et al., 1992). 

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