Figure 4.

(A) Western blot analysis of known amounts of recombinant human α-actin (left) and known amounts of total protein (2.5 μg) from human heart and skeletal muscle tissue (right). Actin was detected using a mouse pAb specific for human α-actin. (B) Western blot analysis of known amounts of recombinant ZASP protein (left) and known amounts of total protein (10 μg) from human heart and skeletal muscle tissue (right). The recombinant protein lacks some amino acids from the NH₂-terminal end of the ZASP sequence, therefore it is slightly smaller in size than the native muscle protein. Mouse pAb to ZASP was used to detect the protein. From densitometric analysis of the bands, it can be calculated that the actin signal from 2.5 μg of total muscle proteins (both heart or skeletal muscle) is approximately equivalent to 500 ng of purified α-actin, whereas for ZASP, there is less protein present in heart than skeletal muscle tissue: 4.5 ng, as opposed to 18 ng in 10 μg of total muscle proteins.