Fig. 4: The trimerization-domain (TD) mutant of human DCP1 abolishes stable trimer formation in solution.

a Mass photometry histograms show that wild-type Hs DCP1 (red) is almost exclusively trimeric, with a major peak at 187 kDa (gray band, “Trimer”) and negligible monomer signal. In contrast, the TD mutant (teal) shifts to a predominant monomer peak at 59 kDa (gray band, “Monomer”) plus a minor dimer shoulder at ~129 kDa. Representative replicate from n = 3 independent measurements. Peak labels denote estimates of apparent masses and may deviate modestly from exact integer multiples due to calibration/peak-picking. b Expanding the mass window reveals additional peaks at ~188 kDa (trimer), 387 kDa (hexamer), 587 kDa (nonamer), and 786 kDa (dodecamer), indicating stepwise self-association of trimers. Representative replicate, n = 3. c The mutant displays peaks at ~60 kDa (monomer), 130 kDa (dimer), and 205 kDa (trimer), but lacks species above 300 kDa, confirming that disruption of the TD suppresses higher-order assembly. Representative replicate, n = 3. In all panels, histograms are plotted as relative frequency versus calculated molecular weight, and shaded gray regions mark the expected mass windows for monomers and trimers.