SEZ6 (Seizure protein 6, also BSRP-C, Brain-specific receptor-like protein C) is a 150 kDa member of the BSRP family of proteins. It is expressed on neurons and exerts an anti branching effect relative to neurite extension.
Mature mouse SEZ6 is a 974 amino acid (aa) type I transmembrane glycoprotein. It contains an extracellular domain (ECD) of at least 876 amino acids (aa 18‑893). The ECD shows three CUB domains and five short consensus repeats (SCRs).
There are two splice variants for SEZ6. One is soluble, and shows an 18 aa substitution for aa 588‑991, while a second shows a deletion of aa 895‑907 plus a 9 aa substitution for aa 982‑991. Over aa 19‑902, mouse SEZ6 is 91% aa identical to human SEZ6.
mRNA expression analysis
Strain specific analysis of SEZ6 mRNA expression in wild-type C57BL/6 mice and B-hSEZ6 mice by RT-PCR. Cerebral cortex RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hSEZ6 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human SEZ6 primers. Mouse Sez6 mRNA was detectable only in wild-type C57BL/6 mice. Human SEZ6 mRNA was detectable only in homozygous B-hSEZ6 mice but not in wild-type mice.
Protein expression analysis
Western blot analysis of SEZ6 protein expression in homozygous B-hSEZ6 mice. Various tissue lysates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hSEZ6 mice (H/H), and then analyzed by western blot with anti-SEZ6 antibody (Abcam, ab314233). 40 μg total proteins were loaded for western blotting analysis. SEZ6 was detected in cerebral cortex, as the antibody is cross-reactive between human and mouse SEZ6. (The arrow above indicates the glycosylated SEZ6 protein, the arrows below indicates the SEZ6 protein 1,2)