Fig. 1.

EPYC1 is an abundant pyrenoid protein. (A) TEM images of Chlamydomonas whole cells and pyrenoid-enriched pellet fraction from cells grown at low CO₂. The yellow arrow indicates the pyrenoid, and green arrows indicate pyrenoid-like structures. (Scale bar: 2 µm.) (B) Mass spectrometry analysis of 366 proteins in pyrenoid-enriched pellet fractions from low- and high-CO₂–grown cells (mean of four biological replicates; raw data are provided in SI Appendix and Dataset S1). RbcL, RBCS, EPYC1, and RCA1 (black) are abundant in low-CO₂ pellets, as determined by iBAQ (y-axis). In addition, these proteins showed increased abundance in low-CO₂ pellets compared with high-CO₂ pellets, as determined by label-free quantification (LFQ; x-axis). (C) Confocal microscopy of EPYC1-Venus and RBCS1-mCherry coexpressed in WT cells. (Scale bar: 5 µm.)