Microtrabecular lattice

Nonmuscle Actin-Binding Proteins Drugs Affecting Actin Polymerization Patterns of Arrangement of Actin Filaments in Animal Cells Three-Dimensional Networks The Microtrabecular Lattice... 

Wolosewick, J.J. Porter. K.R. (1979). Microtrabecular lattice of the cytoplasmic ground substance. Artifact or reality. J. Cell Biol. 82, 114-139. 

The microtrabecular lattice is part of the cytoskeleton and is comprised of an intricate network of fine strands of variable (7-18-nm) diameter. This lattice is made up of many (perhaps up to 400) polypeptides, of which actin is the major component. The cytoplasmic granules appear to be distributed at different depths within this lattice, an organisation that may allow phagosome and granule fusion to occur more efficiently. 

The dominant component of the aqueous compartments in a cell is water, a fraction of which exhibits properties that are known to differ rather markedly from those of pure water. However, the exact proportion of differently structured water is not yet clear. Although the implications of such differences for metabolism and cell ultrastructure remain to be determined, they are likely to be profound. Shown in Figure 1 is a cartoon of Clegg s (1984) proposed ordering of water in the immediate surroundings of the microtrabecular lattice (MTL) of a cell. 

Figure 1. Schematic representations of (A) microtrabecular lattice. Inset at right represents a magnified view of hypotheticai composition of a strand of the lattice (B and C). "Vicinal" and "bound" refer to water (dots) immediately adjacent to a surface, S, and a protein molecule (squiggly line). (From Clegg, 1984).

An electron micrograph of the microtrabecular lattice (magnified 87.450X). 

In the electrochemical interpretation of metabolism presented here, we discount the significance of chemical reactions occurring under conditions well removed from equilibrium as important sources of heat production. Rather, we identify those processes associated with electronic and protonic current flow as the critical elements in heat production. The relationship between body surface area and heat production becomes more readily understandable when it is appreciated that these heat-producing processes take place within cellular membranes (or the microtrabecular lattice). Thus, the finding that heat production is a function of body surface area rather than tissue mass may be a macroscopic reflection of the fact that cellular electrochemical reactions occur in two dimensions, in contrast with three-dimensional, scalar chemical reactions. 

It was also found that the interaction is carried by long molecules which, inside cells, corresponds to the role attributed to the microtrabecular lattice as discussed in Section 3. Furthermore it has been shown that albumin, a globular protein, does not transmit the interaction at physiological concentrations. Albumin can, however, be converted into a transmitter by a treatment that unravels the tertiary structure and allows it to polymerize. 

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