Analysis of cashmere goat meat by label-free proteomics shows that MYL3 is a potential molecular marker of meat toughness

The Inner Mongolia cashmere goat is famous for its bright white cashmere fibre. However, little attention is given to the excellent characteristics of this breed’s meat. We used label-free proteomics to analyse the total protein content in five different muscles, and 1 227 proteins were detected. Through sequential windowed acquisition of all theoretical fragment ions (SWATH), 16, 33, 49, 39, and 31 differentially expressed proteins were successfully detected in the five muscles. Protein–protein interaction network analysis of differentially expressed proteins revealed many strong interactions related to fatty acid beta oxidation and muscle development. Based on SWATH in five muscles, 25 differentially expressed proteins related to muscle development were detected, including seven muscle fibre structural proteins (ACTG2, ACTN4, TAGLN, MYL3, MYL1, MYL6B and MYH4). Finally, immunohistochemical analysis of MYL3 showed that the proportion of MYL3 may be a potential molecular marker for muscle toughness.