Synthesis and turnover of protein-bound Nt-methylhistidine in cultured vascular smooth muscle cells.
Rabbit aortic smooth muscle cells cultured for 14 days in second passage produce significant amounts of protein-bound radioactive Nt-methylhistidine when pulsed with radiolabelled histidine. Much of the radioactive Nt-methylhistidine is located in the actin synthesized by these cells. Pulse chase data also suggest this newly synthesized Nt-methylhistidine disappears from the cell layer at two distinctly different rates: one with a half-life of 2.4 days, and the other with a half-life of approximately 17 days. Radioactive Nt-methylhistidine to histidine ratio reaches a maximum approximately 8 days following the 1-day [14C]histidine pulse. During the initial 15-day chase period, there is a substantial net accumulation of total Nt-methylhistidine in the culture flasks. The data presented in this communication indicate that methods to evaluate Nt-methylhistidine synthesis and disappearance in cultures are feasible when radiolabelled histidine is employed.
D000199:Actins / Q000032:analysis; D000818:Animals; D001011:Aorta; D002478:Cells, Cultured; D006639:Histidine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D008762:Methylhistidines / Q000032:analysis / Q000096:biosynthesis* / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000032:analysis / Q000166:cytology / Q000378:metabolism*; D011817:Rabbits
D000199:Actins; D008762:Methylhistidines; D006639:Histidine; C028118:3-methylhistidine