T-Cell Immunoglobulin And Mucin Domain Containing Protein 4 (TIMD4)

TIM4 has an N-terminal IgV domain, followed by a long mucin stalk and a C-terminal cytoplasmic tail. The IgV domain contains an N-linked glycosylation site and a potential integrin-binding RGD motif, and the mucin stalk contains 38 potential O-linked glycosylation sites and a second N-linked glycosylation site near the membrane. The cytoplasmic domain of TIM4 lacks a conserved tyrosine kinase phosphorylation site found in other TIM family members.

The antigen recognized by the antibody was identified by expression cloning as a type I transmembrane protein called Tim4. Tim4 was expressed in Mac1+ cells in various mouse tissues, including spleen, lymph nodes, and fetal liver. Tim4 bound apoptotic cells by recognizing phosphatidylserine via its immunoglobulin domain.