Protein lactylation in postmortem porcine skeletal muscle: Deciphering muscle-specificity patterns, molecular...

This work aimed to profile lactylation in pork by investigating its variances among muscle types, molecular modification traits, and biochemical regulatory networks. Through integrated immunoblotting, lactylome profiling, and bioinformatics analysis, we demonstrated that protein lactylation increased over postmortem time, with longissimus thoracis muscle exhibiting higher levels than semimembranosus and psoas major muscles. Importantly, this difference was primarily dominated by lactate concentration rather than lactyltransferase p300 levels. The lactylated proteins showed broad molecular weight and isoelectric point ranges, along with modified sites being mainly concentrated in functional random coil regions of proteins and characterized by unique flanking motifs containing arginine (-6) and glycine (+7). Additionally, lactylated proteins were widely localized in cytoplasm and mitochondria, and postmortem energy metabolism comprising phosphagen system, glycolysis, and oxidative phosphorylation was the most notable regulatory network for lactylation. Other pathways were sequentially involved in myofiber contraction, oxidative stress, apoptosis, and calcium homeostasis. Our study provided the first comprehensive characterization of lactylation in pork skeletal muscle, advancing the biological significance of postmortem muscle lactate.