Figure 1. Mutation of the seven regulatory serines and threonines of NPR2 to glutamates increases bone length.

(A) Regulation of NPR2 activity by the phosphorylation state of the seven juxtamembrane serines and threonines on each NPR2 monomer. Purple dots represent phosphates on these serines and threonines. Red lines represent glutamates that are substituted for the serines and threonines. (B) Npr2^7E/7E mice have longer tails. Measurements were made from 17 to 19 live mice of each genotype. (C) X-rays of representative tails from mice euthanized at 18 weeks of age. (D) Increased CA5 vertebra length in Npr2^7E/7E mice compared with wild type, determined from x-ray measurements of tails at 18 weeks of age (10–13 mice of each genotype). (E,F) Longer femurs (E) and tibias (F) in Npr2^7E/7E vs wild type mice. (G) Increased body length in Npr2^7E/7E vs wild type mice. (H) No difference in cranial width comparing Npr2^7E/7E and wild type mice. For E–H, each bar indicates measurements from 10 to 31 mice that were euthanized at the indicated ages. All graphs show mean ±s.e.m. Data were analyzed by unpaired t-tests, with the Holm-Sidak correction for multiple comparisons where appropriate. T-tests rather than ANOVA were used because we were only interested in comparisons between genotypes at a given age, rather than comparisons across ages. *p≤0.05; **p≤0.01; ***p≤0.001.