Aggregates keratin intermediate filaments and promotes disulfide-bond formation among the intermediate filaments during terminal differentiation of mammalian epidermis.
Subcellular locations: Cytoplasmic granule
In the stratum granulosum of the epidermis, localized within keratohyalin granules . In granular keratinocytes and in lower corneocytes, colocalizes with calpain-1/CAPN1 .
Expressed in skin, thymus, stomach, tonsils, testis, placenta, kidney, pancreas, mammary gland, bladder, thyroid, salivary gland and trachea, but not detected in heart, brain, liver, lung, bone marrow, small intestine, spleen, prostate, colon, or adrenal gland . In the skin, mainly expressed in stratum granulosum of the epidermis  .