FIGURE 2.

Molecular components associated with CatSper channel A: topology of pore-forming α-subunits (CATSPER1–4). The α-subunits are 6 transmembrane proteins that contain voltage-sensing domains (VSD; S1–S4), a pore-domain (S5–S6), and a coiled-coil domain at the cytoplasmic COOH termini. B: topologies of ancillary transmembrane proteins associated with CatSper pore-forming channel. Reported include single (CATSPERβ, γ, δ, and ε), 2 (TMEM249), and 3 transmembrane (CATSPERη) subunits and a 12 transmembrane anion transporter (SLCO6C1) with a Kazal domain. C: diagrams of nontransmembrane cytosolic ancillary proteins associated with CatSper channel complex. Reported proteins are shown with conserved motifs/domains in colored boxes; CATSPERζ has an IQ-like motif (LQ-motif), EFCAB9 has EF-hand Ca²⁺ binding domains, and CATSPERτ has a C2 domain.