[Isolation and physico-chemical properties of P-9 protein, marker for the resting cells of lymphoma NK/Ly and Gerene carcinoma].

A fraction of tumour cells in the state of proliferative rest was prepared by sedimentation from aged Ehrlich tumor and lymphoma NK/Ly. These cells do not incorporate [3H]-thymidine and contain fewer proteins and RNAs than the proliferating cells. The incorporation of [3H]-uridine by these cells makes up to 3.5-10% of the maximal incorporation by proliferating cells at the S-phase. The resting cells have a low rate of glycolysis and a high rate of respiration. The activity of lactate dehydrogenase, glucose-6-phosphate dehydrogenase and malate dehydrogenase in these cells is considerably reduced. The resting cell nuclei were found to contain a low molecular weight protein with molecular weight of 9000 +/- 500 (protein P-9) absent in proliferating cell nuclei. Using acetone fractionation and a subsequent preparative electrophoresis in a phenol solution, protein P-9 was isolated from the nuclei of lymphoma NK/Ly and Gerene carcinoma in a pure state. The physico-chemical properties of the protein from various sources were found to be similar. Thus, protein P-9 can be attributed to low molecular weight non-histone proteins with pI at the weakly alkaline region of pH.