CYTOSKELETAL LOGIC - A MODEL FOR MOLECULAR COMPUTATION VIA BOOLEAN OPERATIONS IN MICROTUBULES AND MICROTUBULE-ASSOCIATED PROTEINS

Adaptive behaviors and dynamic activities within living cells are orga nized by the cytoskeleton: intracellular networks of interconnected pr otein polymers which include microtubules (MTs), actin, intermediate f ilaments, microtubule associated proteins (MAPs) and other protein str uctures. Cooperative interactions among cytoskeletal protein subunit c onformational states have been used to model signal transmission and i nformation processing. In the present work we present a theoretical mo del for molecular computing in which Boolean logic is implemented in p arallel networks of individual MTs interconnected by MAPs. Conformatio nal signals propagate on MTs as in data buses and in the model MAPs ar e considered as Boolean operators, either as bit-lines (like MTs) wher e a signal can be transported unchanged between MTs ('BUS-MAP'), or as bit-lines where a Boolean operation is performed in one of the two MA P-MT attachments ('LOGIC-MAP'). Three logic MAPs have been defined ('N OT-MAP', 'AND-MAP', 'XOR-MAP') and used to demonstrate addition, subtr action and other arithmetic operations. Although our choice of Boolean logic is arbitrary, the simulations demonstrate symbolic manipulation in a connectionist system and suggest that MT-MAP networks can perfor m computation in living cells and are candidates for future molecular computing devices.