I-protein a new regulatory protein from vertebrate skeletal muscle. II. Localization.

Rabbit antiserum raised agains I-protein was used for immunofluorescent staining of chicken myofibrils. The FITC-conjugated anti-I-protein antibody stained A-band regions except at their middle regions. According to the conditions used, the myofibrils stained by their fluorescent antibody showed slightly different patterns, i.e., the nonstained regions in the center of the A-bands were wider. On fixing with glutaraldehyde, myofibrils were stained in the A-band regions except at their middle regions. Therefore, I-protein may be localized at A-bands except for the center.