Double phosphorylation of the myosin regulatory light chain during rigor mortis of bovine Longissimus muscle.
To investigate changes in myosin light chains (MyLCs) during postmortem aging of the bovine longissimus muscle, we performed two-dimensional gel electrophoresis followed by identification with matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The results of fluorescent differential gel electrophoresis showed that two spots of the myosin regulatory light chain (MyLC2) at pI values of 4.6 and 4.7 shifted toward those at pI values of 4.5 and 4.6, respectively, by 24 h postmortem when rigor mortis was completed. Meanwhile, the MyLC1 and MyLC3 spots did not change during the 14 days postmortem. Phosphoprotein-specific staining of the gels demonstrated that the MyLC2 proteins at pI values of 4.5 and 4.6 were phosphorylated. Furthermore, possible N-terminal region peptides containing one and two phosphoserine residues were detected in each mass spectrum of the MyLC2 spots at pI values of 4.5 and 4.6, respectively. These results demonstrated that MyLC2 became doubly phosphorylated during rigor formation of the bovine longissimus, suggesting involvement of the MyLC2 phosphorylation in the progress of beef rigor mortis.


BACKGROUND
Bovine; myosin regulatory light chain (RLC, MyLC2); phosphorylation; rigor mortis; skeletal muscle.
Muroya
Susumu
S
Meat Protein Research Team and Animal Product Research Team, National Institute of Livestock and Grassland Science, Tsukuba, Ibaraki, Japan. muros@affrc.go.jp
Ohnishi-Kameyama
Mayumi
M
Oe
Mika
M
Nakajima
Ikuyo
I
Shibata
Masahiro
M
Chikuni
Koichi
K
D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008460:Meat / Q000032:analysis*; D018482:Muscle, Skeletal / Q000378:metabolism*; D018994:Myosin Light Chains / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D012298:Rigor Mortis / Q000378:metabolism*
D018994:Myosin Light Chains; D010750:Phosphoproteins