Table 1.

Quantification of immunogold-labeling of α_i on plasma membranes

Sample*	Number of micrographs†	Gold particles per group‡	Gold particles per μm2
Control	19	3.4  ±  0.4	50 ± 7.1
GDPβS	22	4.7  ±  0.5	61 ± 8.1
GTPγS	24	8.7  ±  0.9	87 ± 7.1

^*Samples are plasma membranes torn from the upper surface of MA104 cells. Controls were fixed immediately, whereas GDPβS and GTPγS samples were incubated with 10 μM nucleotide at 37°C for 30 min before fixation and processing for immunogold labeling with affinity-purified B087 antibodies. 

^†Micrographs were from three independent experiments; each included all three samples. 

^‡Gold particles were grouped on stained structures of variable shape and size (largest dimension, 20–600 nm) on the inner surface of plasma membranes; see ref. 4.