Differences in protein lactylation between pale, soft and exudative and red, firm and non-exudative pork.

This study aimed to understand the development of pale, soft, and exudative (PSE) pork from a new perspective by comparing the differences of lactate-induced protein lactylation and its potential regulators including E1A binding protein p300 (p300) and cAMP response element binding protein (CBP) between PSE and red, firm, and non-exudative (RFN) pork at 1 h postmortem. Results demonstrated that PSE pork presented lower glycogen contents and higher lactate levels than RFN pork (P < 0.05). Meanwhile, p300/CBP and protein lactylation levels in PSE pork were higher (P < 0.05). Besides, the immunofluorescence results showed that p300/CBP and lactylated proteins were predominantly localized around the nucleus and sarcolemma membrane with small amounts in the cytoplasm, and these distribution signals were intensified in PSE pork. Importantly, a high degree of co-localization of p300/CBP and lactylated proteins was also observed in postmortem myocytes, confirming that p300/CBP were the critical regulators of lactylation modification in postmortem muscle. This work for the first time demonstrates that protein lactylation levels between PSE and RFN pork were notably diverse, which may potentially be involved in the regulation of various postmortem muscle biochemical metabolism.