• The protein encoded by EDNRB is a G protein-coupled receptor which activates a phosphatidylinositol-calcium second messenger system. Its ligand, endothelin, consists of a family of three potent vasoactive peptides: ET1, ET2, and ET3. Studies suggest that the multigenic disorder, Hirschsprung disease type 2, is due to mutations in the endothelin receptor type B gene. Alternative splicing and the use of alternative promoters results in multiple transcript variants.
• The CDS that encodes human EDNRB signal peptide and extracellular domain, transmembrane and cytoplasmic domain, followed by mouse 3’UTR-STOP is inserted right after mouse Ednrb ATG to replace the exon 1 of mouse Ednrb gene. The EDNRB protein expression will be driven by endogenous mouse Ednrb promoter, while mouse Ednrb gene transcription and translation will be disrupted. 
• EDNRB protein was detected in cortex, liver, spleen, lung and kidney from wild-type C57BL/6 mice and homozygous B-hEDNRB mice as the antibody is cross-recognize with human and mouse.
• Mouse Ednrb mRNA was detectable only in wild-type C57BL/6 mice. Human EDNRB mRNA was detectable only in homozygous B-hEDNRB mice, but not in wild-type C57BL/6 mice. 
• All homozygous B-hEDNRB mice have a coat color phenotype, with white fur on the abdomen.

Species specific analysis of EDNRB gene expression in wild-type C57BL/6 mice and homozygous humanized B-hEDNRB mice by RT-PCR. Lung were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hEDNRB mice (H/H). Mouse Ednrb mRNA was detectable only in wild-type C57BL/6 mice. Human EDNRB mRNA was detectable only in homozygous B-hEDNRB mice, but not in wild-type C57BL/6 mice. 

Western blot analysis of EDNRB protein expression in homozygous B-hEDNRB mice. Various tissue lysates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hEDNRB mice (H/H), and then analyzed by western blot with anti-EDNRB antibody (abcam, ab129102). 30 μg total proteins were loaded for western blotting analysis. EDNRB was detected in cortex, liver, spleen, lung and kidney from wild-type C57BL/6 mice and homozygous B-hEDNRB mice as the antibody is cross-recognize with human and mouse.