ABPs in cells

Actin Binding Proteins in cells

Actin is a very abundant protein in cells and exists in a variety of different structures within the same cell. Just how the cell is able to organise its actin into these different structures and keep them and their associated ABPs apart is a problem in cell biology. The answer is likely to be from multiple separate sources. Specific messenger RNA are located in different regions of the cell, this is likely to form part of the explanation. Another is that some ABPs are modulated by and physically associated with phosphoinositides (Takenawa & Itoh, 2001) such as PIP₂, and so are held close to the cell membrane. The various actin iso-forms themselves are also differentially distributed in different regions of the cell for example b-actin, a very minor constituent of muscle is present just under the cell membrane. This is likely to be due to differential binding to immobilized components.

References:-

Gu, W., Pan, F., Zhang, H., Bassell, G. J. & Singer, R. H. (2002) A predominantly nuclear protein affecting cytoplasmic localization of b-actin mRNA in fibroblasts and neurons, JCB. 156, 41-51.

Hofer, D., Ness, W. & Drenckhahn, D. (1997). "Sorting of actin isoforms in chicken auditory hair cells." J.Cell Sci. 110, 765-770.

Takenawa, T. & Itoh, T. (2001) Phosphoinositides, key molecules for regulation of actin cytoskeletal organization and membrane traffic from the plasma membrane., BBA. 1533, 190-206.