Isolation and properties of a basic protein from skeletal-muscle sarcoplasm.

1. An isolation procedure for preparing gram quantities of a previously undescribed protein from muscle is presented. 2. The protein amounts to over 2% of the sarcoplasmic proteins of pig longissimus dorsi muscle, but does not correspond to any glycolytic enzyme, nor to any of several other enzymes that have been tested for. 3. The protein is isoelectric between pH8.5 and 9.0, has mol.wt. 34500+/-500 and has E(1%) (281mmu) 20.7. 4. The identities of nearly all the major protein bands obtained in electrophoresis on starch gel of pig longissimus dorsi muscle sarcoplasm have been established.