Accumulation of Tropomyosin in Developing Chicken Gizzard Smooth

et al. (1989) J. Biochem. 105, 712-717). At the early stages of development, the amount of these isoforms was larger than those of a and ff isoforms. However, they gradually decreased at later stages and finally disappeared completely after hatching. By using two-dimensional gel electrophoresis and an image analyzing system, we examined the process of tropomyosin accumulation in gizzard smooth muscle development. The accumu-lation patterns of tropomyosin isoforms and their relative molar ratios to actin in embry-onic development were different from those in the stages after hatching. The relative molar ratio of tropomyosin to actin in the thin filament preparation of embryonic gizzards was lower than that of adult, and it gradually increased in the course of embryonic develop-ment. In differentiating smooth muscle, specific proteins accumu-late in a specific manner (1). Studies on the accumulation of smooth muscle proteins provide us with basic information essential to the understanding of smooth muscle differ-entiation (1-4). Especially, we consider that the nature o