Native rabbit cardiac muscle contains cTnI phosphorylated at Ser-150.
A, Western blot of two-dimensional isoelectric focusing-separated rabbit ventricular myofibrils probed with the pTnI 150 antibody identified three cTnI species as containing Ser-150 phosphorylation (P1, P2, and P3). B, sequential probing of the same membrane with a total cTnI antibody identified four cTnI species. Alignment of the two membranes demonstrates the three most acidic, phosphorylated cTnI species were detected by the pTnI 150 antibody as containing Ser-150 phosphorylation without detection of the non-phosphorylated, basic species (U).