Table 1.

Cryo-EM data collection, refinement and validation statistics

	IFT-A_ Elongated (EMD-34893)	IFT-A_ Folded (EMD-34894)	IFT-A_ Base-1 (EMD-34895) (PDB 8HMC)	IFT-A_ Base-2 (EMD-34896) (PDB 8HMD)	IFT-A_ Head-1 (EMD-34897) (PDB 8HME)	IFT-A_ Head-2 (EMD-34898) (PDB 8HMF)	IFT-A_ Head-3 (EMD-34899)
Data collection and processing
Magnification	×81,000	×81,000	×81,000	×81,000	×81,000	×81,000	×81,000
Voltage (kV)	300	300	300	300	300	300	300
Electron exposure (e–/Å2)	50.0	50.0	50.0	50.0	50.0	50.0	50.0
Defocus range (μm)	1.5–2.5	1.5–2.5	1.5–2.5	1.5–2.5	1.5–2.5	1.5–2.5	1.5–2.5
Pixel size (Å)	1.10	1.10	1.10	1.10	1.10	1.10	1.10
Symmetry imposed	C1	C1	C1	C1	C1	C1	C1
Initial particle images (no.)	1,225,162	101,666	1,239,500	1,239,500	1,225,162	1,225,162	1,225,162
Final particle images (no.)	35,628	14,020	538,078	86,362	386,801	199,946	41,877
Map resolution (Å)	8.5	8.8	3.6	4.7	4.2	4.6	6.0
FSC threshold	0.143	0.143	0.143	0.143	0.143	0.143	0.143
Map resolution range (Å)	7.0–14.0	7.0–12.0	3.2–5.0	4.0–8.0	4.0–6.0	4.0–8.0	5.5–10.0
Refinement
Initial model used (PDB code)			n/a	n/a	n/a	n/a
Model resolution (Å)			n/a	n/a	n/a	n/a
FSC threshold			n/a	n/a	n/a	n/a
Model resolution range (Å)			n/a	n/a	n/a	n/a
Map sharpening B factor (Å2)			−106	−120	−126	−152
Model composition
Non-hydrogen atoms			21,797	27,372	22,169	25,330
Protein residues			2693	3387	2745	3135
Ligands			2	2	2	2
B factors (Å2)
Protein			72.06	117.41	78.33	86.15
Ligand			174.17	336.87	116.42	127.01
R.m.s. deviations
Bond lengths (Å)			0.011	0.003	0.002	0.002
Bond angles (°)			1.060	0.619	0.587	0.599
Validation
MolProbity score			1.87	1.88	1.93	1.87
Clashscore			8.57	9.86	11.78	11.53
Poor rotamers (%)			0.13	0.03	0.00	0.04
Ramachandran plot
Favored (%)			93.97	944.70	95.11	95.78
Allowed (%)			6.00	5.24	4.71	4.03
Disallowed (%)			0.04	0.06	0.18	0.19