Figure 1.

Peripherin is as abundant as the NF triplet in the adult PNS and exists in a relatively fixed stoichiometry with these subunits. Peripherin was identified as one of the major proteins in the sciatic nerve of 3-month-old mice by Coomassie blue staining (A) and is Triton X-100 insoluble (B). The peripherin protein was recognized by anti-peripherin antibody on immunoblot (C). The 57 kDa peripherin band stained by Coomassie blue is contaminated by another Triton X-100-insoluble protein (p57) as evidenced by its presence in peripherin knock-out mice (D), and peripherin deletion was confirmed by immunoblotting with specific anti-peripherin antibody (E). Measurement of peripherin and NFL in sciatic nerve homogenates by quantitative immunoblotting (F, G). Purified peripherin with a 26 kDa GST tag or purified NFL was used as standard in separate immunoblots and incubated with either anti-peripherin or anti-NFL. F, Lanes 1, 2, 3, Purified peripherin at 40, 80, and 160 ng, respectively. G, Lanes 1, 2, 3, Purified NFL at 9, 18, and 36 ng, respectively. Lanes 4–11, Homogenates from eight different sciatic nerves of eight mice. Peripherin is as abundant as the NF triplet in the adult PNS and exists in a relatively fixed stoichiometry with these subunits. The molar ratio is estimated to be 3.5:1 (NFL/peripherin) based on quantitative immunoblotting (H). NF triplets were identified by immunoblotting with specific antibodies and also by their disappearance in Triton X-100-insoluble fractions from corresponding knock-out mice (NFH knock-out, NFM knock-out, and NFL knock-out). Note that the 68 kDa Triton X-100-soluble protein (B), which contaminates NFL in homogenates (A), was previously identified as serum albumin (Soifer et al., 1981). Per, Peripherin; Pel, pellet; Sol, soluble; wt, wild-type; pko, peripherin knock-out.