because there is enough tropomyosin for two tropomyosin molecules to be associated with each of the short actin filaments in the membrane skeleton , the erythrocyte membrane tmbp , together with tropomyosin , could function to restrict the number of spectrin molecules attached to each of the short actin filaments and thus specify the hexagonal symmetry of the spectrin-actin lattice .
C0025979
actin filaments
C0001271
actin