The ability of actinic light to modify the bacteriorhodopsin photocycle revisited: heterogeneity vs photocooperativity.

In 1995, evidence both for photocooperativity and for heterogeneity as possible explanations for the ability of actinic light to modify the kinetics and pathways of the bacteriorhodopsin (BR) photocycle was reviewed ( Shrager, R. I., Hendler, R.

Diffusion delays and unstirred layer effects at monolayer cultures of Chinese hamster ovary cells: radioligand binding, confocal microscopy, and mathematical simulations.

Cells grown in monolayer culture offer a convenient system for binding and other experiments under conditions that preserve the complexity of the living state. Kinetics experiments, however, may be distorted by the time course of drug penetration into even so simple a "tissue" as the monolayer. The impediments include unstirred layers both above and between the cells, the congregation of receptors within the confined space between cells, and nonspecific binding to membrane components.