The protein encoded by this gene is a membrane receptor for both human hepatitis A virus (HHAV) and TIMD4. The encoded protein may be involved in the moderation of asthma and allergic diseases. The reference genome represents an allele that retains a MTTVP amino acid segment that confers protection against atopy in HHAV seropositive individuals. Alternative splicing of this gene results in multiple transcript variants. Related pseudogenes have been identified on chromosomes 4, 12 and 19. [provided by RefSeq, Apr 2015],function:May play a role in T-helper cell development and the regulation of asthma and allergic diseases. Receptor for TIMD4 (By similarity). In case of human hepatitis A virus (HHAV) infection, functions as a cell-surface receptor for the virus.,polymorphism:HHAV seropositivity protects against atopy in individuals with the variants Met-Thr-Thr-Val-Pro-157 ins and Met-Thr-Thr-Thr-Val-Pro-157 ins. Modernisation has led to a reduction in HAV seroprevalence and thus, may be, to an increase of expression of atopy, such as asthma, allergic rhinitis and atopic dermatitis. Allelic variation does not affect HAV-infection rates in Caucasians, Asians and African Americans.,similarity:Belongs to the immunoglobulin superfamily. TIM family.,similarity:Contains 1 Ig-like V-type (immunoglobulin-like) domain.,tissue specificity:Widely expressed, with highest levels in kidney and testis. Expressed by activated CD4+ T-cells during the development of helper T-cells responses.,