Serpin B13
Known alternatively as hurpin or proteinase inhibitor 13 (PI13), Serpin B13 completes the chromosome 18 intracellular clade B cluster. Expression is prominent in liver and skin, and the protein has been reported in psoriatic lesions, certain carcinomas and the pituitary, where early work suggested hormonally regulated expression. Its inhibitory specificity is unresolved, but the serpin fold positions a reactive loop for trapping serine proteases within the cytosol, likely contributing to protection against protease-driven cell death. Elevated hurpin levels in tumors have raised interest in SERPINB13 as a biomarker, and recombinant Serpin B13 aids studies of intracellular proteostasis and clade B redundancy.
