Thiol protease which is believed to participate in intracellular degradation and turnover of proteins . Cleaves matrix extracellular phosphoglycoprotein MEPE . Involved in the solubilization of cross-linked TG/thyroglobulin in the thyroid follicle lumen (By similarity). Has also been implicated in tumor invasion and metastasis .
Subcellular locations: Lysosome, Melanosome, Secreted, Extracellular space, Apical cell membrane
Identified by mass spectrometry in melanosome fractions from stage I to stage IV . Localizes to the lumen of thyroid follicles and to the apical membrane of thyroid epithelial cells (By similarity).
Expressed in the stratum spinosum of the epidermis. Weak expression is detected in the stratum granulosum.