Fig. 2. Western blot analysis with SERCA 1- and SERCA 2-specific antibodies reveals the expression of SERCA 1 in heater cells. Two peptides, one corresponding to amino acids 328-342 of blue marlin SERCA 1B and one corresponding to amino acids 192-205 of rabbit SERCA 2, were used to synthesize isoform-specific Ca²⁺-ATPase antibodies. The SERCA 1 antibody labeled an approximately 110 kDa band in superior rectus extraocular muscle, heater organ and fast-twitch muscle, while the SERCA 2 antibody labeled atrium, ventricle and slow-twitch muscle. BMSR, blue marlin superior rectus muscle; BMHO, blue marlin heater organ; BMFT, blue marlin fast-twitch skeletal muscle; BMCard, blue marlin cardiac muscle; BFTFT, bluefin tuna fast-twitch skeletal muscle; BFTST, bluefin tuna slow-twitch skeletal muscle; BFTAt, bluefin tuna atrial muscle; BFTVent, bluefin tuna ventricular muscle; YFTFT, yellowfin tuna fast-twitch skeletal muscle; YFTST, yellowfin tuna slow-twitch skeletal muscle.