Figure 3. Amino acids contribute the majority of cell mass for proliferating mammalian cells.

(A) Serine and valine carbon each contribute 2–4% of cell dry mass in mammalian cells. (B) A pooled mixture of fifteen amino acids can label the majority of cellular carbon in proliferating mammalian cells. Amino acid mass contribution was determined by culturing cells in modified RPMI (Table S2, Figure S3A) with [U-¹⁴C]-amino acids. Mass contribution of glucose and glutamine as determined in D are also presented for comparison. (C) The fraction of cellular nitrogen derived from glutamine α- and amide-nitrogen atoms. (D) Acetate carbon is a minor contributor to cell mass, and the net contribution is dependent on acetate concentration. (E) Contribution of serum palmitate to cell mass as determined by incorporation of [U-¹⁴C]-palmitate. Each bar represents the average of N=3 replicates, ±S.D.