Mitochondrial mRNA localization is governed by translation kinetics and spatial transport
Fig 2
Instantaneous model is insufficient to explain differential mitochondrial localization of different gene groups.
(A) Cumulative distributions of conditional and constitutive mRNA genes vs number of binding-competent ribosomes β (lines indicate fraction of genes with given β or less). β for each mRNA gene is calculated from gene-specific kinit and kelong that are estimated from experimental data (see Methods). Inset is cumulative distribution of ribosome occupancy [38], showing ribosome occupancy and β have similar distributions. (B) Violin plot [41] showing mRNA localization fraction of individual genes with instantaneous model (no maturation delay), with translation kinetics for each gene estimated from experimental data (see Methods). 4% MVF. For direct comparison to experimental data, mRNA in region 1 (see Fig 1D) recorded as mitochondrially localized. (C) Mitochondrial localization vs mitochondrial volume fraction for TIM50 and ATP3 with instantaneous model (solid lines), with translation kinetics for both genes estimated from experimental data (see Methods). For direct comparison to experimental data (dotted lines with circles), mRNA in regions 1 and 2 (see Fig 1D) recorded as mitochondrially localized. (D) Cumulative distributions of MTS exposure time texpo = (L − lMTS)/kelong. The steeper rise of conditional genes indicates more conditional gene mRNAs have low exposure times. Translation kinetics for each gene estimated from experimental data (see Methods). Inset shows the cumulative distribution of elongation rate, for which constitutive genes have a steeper rise, indicating slower typical elongation, which contributes to the longer exposure times in the main plot.