Extracellular matrix protein that plays a role in epidermal differentiation and is required for epidermal adhesion during embryonic development. Interacts with FREM2. Localizes at the basement membrane zone of embryonic epidermis and hair follicles. Expressed in epidermis and hair follicles. Expressed in many developing epidermal appendages, including the whisker and sensory vibrissae, cranial and trunk hair follicles, meibomian glands, teeth, footpads, eyelash primordia and invaginating mammary glands. Limb expression localizes to sheets of dermal cells on the apical and basal surfaces of the digits but, unlike FRAS1, is excluded from the apical ectodermal ridge. Usually expressed at higher level in dermal cells underlying the differentiating epithelial components, especially underlying the epidermis of the head, limbs, and eyelids. Expression in the eyelid dermis is apparent as early as 13 dpc. Postnatal expression in the skin is limited to the dermal papillae. In the kidney, it is expressed from 12.5 dpc in the mesenchyme surrounding the branching ureteric tree, with a strong expression in the more proximal regions of these tubules rather than at the proliferating and branching ends of the ureteric buds. In hair follicle, it is selectively expressed in the vibrissal hair primordia during development. Preferentially expressed in the whisker pad epithelia of 12.5 dpc embryos, in both the epithelial and mesenchymal cells of developing hair follicles. In the early stages of hair follicle development (i.e. stages 0-1), it is expressed in both hair placodes and dermal condensations. In stage 2, it is detected in dermal condensations and adjacent epithelia, but not in the upper region of the hair follicles. Expressed at the tip of developing hair follicles in the later stages (i.e. stages 3-5). Expressed in the embryos of all stages examined and in some adult tissues including eye, kidney, ovary, urinary bladder and testes; however, the overall expression levels in adult tissues are relatively low compared with those in embryonic tissues. The Calx-beta domain binds calcium with high affinity and undergo a major conformational shift upon binding. Defects in Frem1 are the cause of head blebs (heb) which is a spontaneous mutation that is characterized by absent or malformed eyes, which are often open at birth. Cryptophthalmos is noted in all heb homozygous animals, as is occasional hindlimb polydactyly. Was termed QBRICK because it contains 12 repeats: 'Q' stands for queen and is taken from the queen being the 12th in a suit of playing card, and 'BRICK' stands for the repeating unit. Frem1 also corresponds to a N-ethyl-N-nitrosourea-induced allele called 'bat'. Homozygous bat mice display similar phenotype than heb mice. Belongs to the FRAS1 family.