Cell surface glycoprotein that participates in iron homeostasis in the liver, the kidney, the retina and oligodendrocytes by acting as a receptor of H-ferritin (PubMed:16203866, PubMed:33065090). Mechanistically, mediates iron-containing ferritin uptake via an endocytic pathway, trafficking to endosomes and subsequently to lysosomes (PubMed:16043519, PubMed:21886823). Plays also an important role in the regulation of Th2 immunity (PubMed:16043519). Receptor for SEMA4A involved in the regulation of T-cell function, enhancing T-cell activation (PubMed:12374982). Homodimer. Expressed on late differentiated Th2 cells (PubMed:16043519). Expressed also on all splenic B-cells, with increased levels on germinal center B-cells, in the liver, especially in bile duct epithelial cells, and in renal tubule cells (PubMed:16203866). Within retina, mainly expressed in Mueller cells (PubMed:33065090). Deletion mutants lead to ferritin accumulation and iron overload in the retina leading to retinal lesions. Belongs to the T-cell and airway phenotype regulator (Tapr) locus, a single chromosomal region that confers reduced T-helper type 2 responsiveness and protects against airway hyperactivity (AHR), the hallmark of human asthma. The human genomic locus appears to lack the Timd2 gene. Belongs to the immunoglobulin superfamily. TIM family.