Upstream sequences of orthologous genes are more conserved than paralogous genes. The maximal sequence identities of all 100-bp segments within a 150-bp sliding window were computed for each gene pair. The x-axis represents the end position of the sliding window relative to the translation-start codon. The y-axis represents the percentage sequence identities. Shown are the average of 100-bp-segment maximal identities of all orthologous (solid lines with standard deviation) gene pairs in Pcdhα (A) andPcdhγ (B) gene clusters. Also shown are the maximal identities between each gene and all the other paralogous members (excluding C-type protocadherin genes) of the same gene cluster (broken lines without standard deviation). The maximal identities for each orthologous gene pair in C-type protocadherin genes are shown individually in C. Note that the conserved region upstream of C-type protocadherin genes is larger than that of other protocadherin genes.
