Fig. 11.

Immunogold labeling for the plasma membrane Ca²⁺ pump in the hair bundle. A: labeling of THC hair bundle at the middle location with PMCA2 antibody. B: labeling of SHC hair bundle at the middle location with PMCA2 antibody. Note in A and B that the apical plasma membrane is also labeled. C: mean gold particle density for labeling for PMCA2a (F2A antibody) for apical, middle, and basal THCs and SHCs; each bar is the mean ± SE of 10 micrographs. D: transverse gradient in labeling for PMCA2 using the NR2 antibody: gold particle density (PC) plotted vs. the number of hair cells (R) across the papilla from the neural edge. Smooth curve is fit: PC = PC₁ + PC₂/{1 + exp[−(R − R_0.5)/R_S]}, where PC₁ = 33 counts, PC₁ + PC₂ = 17 counts, R_0.5 = 12 hair cells across, and slope R_S = 1.0.