In chapters II-V we developed the theory of one-stage chemoreception, in which a ligand can only be absorbed by a cell by a direct hit on the binding site of the receptor molecule. In chapter VIII the theory will be extended to incorporate two-stage capture processes in which the ligand is first incorporated in the cell membrane and then diffuses laterally in the plane of the membrane till it hits a binding site. Actually, two-stage chemoreception is only one of a variety of processes which occur at the surface of the living cell and in which the lateral translational - or rotational diffusion of proteins plays an essential role. It is for this reason that the experimental determination of the relevant diffusion coefficients has been pursued vigorously during the last decade [37–44]. Experimental values of the the lateral translational diffusion coefficient (DT’) range from 10-8 to 10-11 cm2 s-1. For the rotational diffusion coefficient (DR’) of proteins embedded in the cell membrane one measures values in the range from 105 to 103 s-1.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Diffusion and Flow in the Cell
Frederik W. Wiegel
- Springer Berlin Heidelberg
ec4u, Neuer Inhalt/© ITandMEDIA