Journal of Cell Science· 2026Q2
SPEF1 mediates assembly of central pair microtubule complexes in cilia of Tetrahymena
- 1citations
- Q2SCImago
- 2026year
Short summary
SPEF1 protein is essential for assembling central pair microtubule complexes in cilia, with its loss causing structural defects throughout the ciliary middle segment in Tetrahymena.
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Key points
- SPEF1 loss disrupts central pair microtubules in the ciliary middle segment, causing gaps and truncations.
- SPEF1 localizes to both central and outer doublet microtubules within cilia, with enrichment near the distal tip.
- SPEF1 particles are largely stationary and turn over slowly, not participating in intraflagellar transport.
- Central pair defects caused by SPEF1 loss occur early during ciliary assembly.
AI-generated from the title and abstract; the full text is not read.
Abstract
SPEF1 is a conserved calponin-homology domain protein that decorates the seam of central pair microtubules in the distal segment of motile cilia. Here, we show that in the ciliate Tetrahymena, loss of SPEF1 disrupts the central pair throughout the middle segment, which comprises most of the cilium, producing gaps in the microtubule lattice, truncations of proximal microtubule regions, and loss of lateral projections. Although visible structural defects were restricted to the central microtubules, SPEF1 also localized to the ciliary outer doublets and to all classes of non-ciliary cortical microtubules. Within cilia, SPEF1 was strongly enriched near the distal tip but was also present throughout the middle segment, where it was more abundant on the central than on the outer doublet microtubules. In live cilia, most SPEF1 particles were stationary and turned over slowly; some underwent diffusion, but none moved by intraflagellar transport. Central pair defects arose early during ciliary assembly. We propose that SPEF1 functions as a general microtubule stabilizer whose activity is particularly important for the assembly of central pair microtubules within the middle ciliary segment.
The authors' abstract, as published at the source. Journal of Cell Science, 2026 · DOI ↗
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Field: Genetics (Biochemistry, Genetics and Molecular Biology)
GeneticsBiochemistry, Genetics and Molecular Biology