Transition of beta-actinin isoforms during development of chicken skeletal muscle.
We examined by means of the immunoblotting technique the transition of beta-actinin isoforms during the development of the chicken from 5 day embryo to adult. As an antigen, beta-actinin was prepared from adult chicken breast muscle (pectoralis major) and polyclonal antibody was obtained by injecting undenatured beta-actinin into a rabbit. Immunoblotting examination of breast muscle at several stages of development (except 5 day embryo, in which the whole body minus the head and limbs was examined) showed that the species of beta-actinin subunits change during development: 1) beta I is already present in 5 day embryo, whereas beta II appears only after 9 days. 2) In 5 day embryo, we found, instead of beta II, a new subunit (designated beta III) that cross-reacts with the antibody, has the apparent molecular weight of 30,000 daltons and has a slightly alkaline isoelectric point compared with beta I. The content of beta III gradually decreased and beta III completely disappeared a week after hatching. Such a type of transition of the isoforms in beta-actinin subunits is similar to that observed in other muscle proteins. The transition of beta-actinin isoforms may correlate to the organization of an I-Z-I brush, especially to the length determination of thin filaments, because the developmental stage at which beta III disappears coincides with that at which the length of thin filaments is strictly determined.
Asami
Y
Y
Department of Physics, School of Science and Engineering, Waseda University, Tokyo.
Funatsu
T
T
Ishiwata
S
S
D000185:Actinin / Q000235:genetics* / Q000302:isolation & purification; D000818:Animals; D002642:Chick Embryo; D009132:Muscles / Q000196:embryology* / Q000378:metabolism; D009210:Myofibrils / Q000378:metabolism / Q000648:ultrastructure; D014176:Protein Biosynthesis
D000185:Actinin