TABLE 2.

Insulin receptor affinities, concentrations, and fiber composition measured in different rat muscle fibers

Muscle	Total concentration of insulin binding sites (bt)*	Receptor affinity (K)	Fiber composition (% slow twitch)	Rate of insulin binding (k+ = k−/K)†
Adductor longus	503 nM	0.92 nM	88	0.0022 nM−1 s−1
Soleus	596 nM	2.06 nM	84	0.0010 nM−1 s−1
Quadriceps	88 nM	0.258 nM	8	0.0078 nM−1 s−1
EDL	479 nM	1.82 nM	3	0.0011 nM−1 s−1
Anterior tibialis	165 nM	1.03 nM	2	0.0019 nM−1 s−1
Medial gastrocnemius	188 nM	1.01 nM	4	0.0020 nM−1 s−1

Data is from Koerker et al. (15).

^*Assuming t-tubules constitute 0.3% of the fiber volume (16).

^†k₋ = 2 × 10⁻³ s⁻¹ (21).