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The Sema domain, a protein interacting module, of semaphorin 3B (Sema3B) Sema3B is coexpressed with semaphorin 3F and both proteins are candidate tumor suppressors. Both Sema3B and Sema3F show high levels of expression in normal tissues and low-grade tumors but are down-regulated in highly metastatic tumors in the lung, melanoma cells, bladder carcinoma cells and prostate carcinoma. They are upregulated by estrogen and inhibit cell motility and invasiveness through decreased FAK phosphorylation and inhibition of MMP-2 and MMP-9 expression. Two receptor families, the neuropilins (NP) and plexins, have been implicated in mediating the actions of semaphorins 3B and 3F. Sema3B is a member of the class 3 semaphorin family of proteins. Semaphorins are regulatory molecules in the development of the nervous system and in axonal guidance. They also play important roles in other biological processes, such as angiogenesis, immune regulation, respiration systems and cancer. The Sema domain is located at the N-terminus and contains four disulfide bonds formed by eight conserved cysteine residues. It serves as a receptor-recognition and -binding module. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",