The linker for activation of T-cells protein (LAT) is a single-pass transmembrane protein with multiple tyrosine residues that can act as binding sites for different effector proteins when phosphorylated. There are four isoforms of LAT in humans that are functionally equivalent, with isoform a being the most common. Although there is no existing model for LAT, we have made predictions of some structural features using different tools. Primary sequence analysis confirms that these structural features are conserved across LAT proteins in different species. LAT is an important scaffold protein in T-cell receptor signalling pathways, recruiting many downstream effectors to the correct location for their activation. Hence, mutations in LAT can cause abnormal T-cell function such as fatal lymphoproliferative disease.