Pumps terms Links

In erythrocytes and most other cells, the major structural link of plasma membranes to the cytoskeleton is mediated by interactions between ankyrin and various integral membrane proteins, including Cf/HCOj antiporters, sodium ion pumps and voltage-dependent sodium ion channels. Ankyrin also binds to the =100 nm, rod-shaped, antiparallel a(3 heterodimers of spectrin and thus secures the cytoskeleton to the plasma membrane. Spectrin dimers self-associate to form tetramers and further to form a polygonal network parallel to the plasma membrane (Fig. 2-9D). Neurons contain both spectrin I, also termed erythroid spectrin, and spectrin II, also termed fodrin. Spectrin II is found throughout neurons, including axons, and binds to microtubules, whereas spectrin I occurs only in the soma and dendrites. 

According to Papa,137 the mechanism which links the redox enzymes with the ATPase complex is the proton flow. Each of these complexes is linked with the other complexes through the proton flow. In terms of thermodynamics the functioning of the primary proton pump results in an electrochemical potential gradient across the membrane, which includes the concentration and electric terms ... 

Unlike simple data logging systems, supervisory control systems are designed to restrict the flexibility of the operator by "supervision" of his actions. In these systems the operator can interact with the plant through the keyboard/workstation to start or stop pumps, open valves and change PID controller set points. The three-term controllers may be conventional electronic controllers, linked to the supervising system, or software algorithms programmed into a PLC. 

Primary active transport occurs when the transport of a substrate is coupled to an energy-yielding metabolic reaction. The energy required may come from several different sources (a) the high-energy compound ATP used by a specific ATPase (ATPase pump) (b) energy from the electron transport system released as electrons that flow down the cytochrome chain (redox-pump) and (c) the electric field produced by free radicals. Implicit in these three theories is the participation of ions and ion transport. Secondary active transport is a term often used to denote the transport of one substrate linked to the flow of a second substrate. Wilbrandt (1975) refers to this as flow-coupled active transport it may be this form of transport that is most often involved in the active uptake of sugars and amino acids. A review of some models of carrier-mediated active transport transport has recently been presented by Crane (1977). 

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