• SORT1 (Sortilin) is a vital regulator that reduces PGRN levels in plasma and the brain by transporting it into cells for degradation. It's also a transmembrane protein overexpressed in many cancers, playing a key role in protein internalization, sorting, and transportation.
• The coding sequences of human SORT1 were inserted to replace part of murine exon 2 and all of exon 3-16. The insertion disrupts the endogenous murine Sort1 gene, resulting in a non-functional transcript in B-hSORT1 mice.
• In multiple tissue tests including lung, brain, kidney, and testicle, mouse SORT1 was detectable only in wild-type mice. Human SORT1 was detectable only in homozygous B-hSORT1 mice plus.

Strain specific analysis of SORT1 mRNA expression in wild-type C57BL/6 mice and B-hSORT1 mice plus by RT-PCR. Brain RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hSORT1 mice plus (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human SORT1 primers. Mouse Sort1 mRNA was detectable in wild-type C57BL/6 mice. Human SORT1 mRNA was detectable only in homozygous B-hSORT1 mice plus but not in wild-type mice.

Strain specific SORT1 expression analysis in wild-type C57BL/6 mice and homozygous B-hSORT1 mice plus by western blot. Lung, brain, kidney and testicle tissue were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hSORT1 mice plus (H/H) and analyzed by western blot with anti-SORT1 antibody. Mouse SORT1 was detectable only in wild-type mice. Human SORT1 was detectable only in homozygous B-hSORT1 mice plus.