Sfr1 localizes broadly throughout the basal body microtubule scaffold Sfr1 localizes broadly throughout the basal body microtubule scaffold. immunoEM of N-terminally tagged MTT1pr-GFP-Sfr1 cells. Sfr1 localizes broadly throughout the basal body microtubule scaffold. immunoEM of N-terminally tagged MTT1pr-GFP-Sfr1 cells. (A) Serial sections reveal a majority of Sfr1 (gold particles) within the midpoint region of the basal body. Sfr1 localizes primarily along the microtubule scaffold (arrowheads). Scale bar, 100 nm. The schematized basal body indicates the proximal, midpoint, and distal regions used for quantification in panel B. (B) Quantification of the ultrastructural basal body localization of Sfr1 is based on data from seven complete serial sections from three different cells (a total of 201 gold particles). Sfr1 localizes primarily to the proximal and midpoint regions (85.5% total), with a small population at the distal end (5%) and peripheral to the basal body along the accessory structures (9.5%). Westley Heydeck et al. mSphere 2016; doi:10.1128/mSphere.00257-16