Chemokine (C motif) ligand (XCL1) is a small cytokine belonging to the C chemokine family that is also known as lymphotactin. Chemokines are known for their function in inflammatory and immunological responses. This family C chemokines differs in structure and function from most chemokines. There are only two chemokines in this family and what separated them from other chemokines is that they only have two cysteines; one N-terminal cysteine and one cysteine downstream. These both are called Lymphotactin, alpha and beta form, and claim special characteristics only found between the two. Lymphotactins can go through a reversible conformational change which changes its binding shifts. In normal tissues, XCL1 is found in high levels in spleen, thymus, small intestine and peripheral blood leukocytes, and at lower levels in lung, prostate gland and ovary. Secretion of XCL1 is responsible for the increase of intracellular calcium in peripheral blood lymphocytes. Cellular sources for XCL1 include activated thymic and peripheral blood CD8+ T cells. NK cells also secrete XCL1 along with other chemokines early in infections. XCR1 expressing dendritic cells (DC) are a major target of XCL1. In humans, XCL1 is closely related to another chemokine called XCL2, whose gene is found at the same locus on chromosome 1. Both of these chemokines share many genetic and functional similarities; however XCL2 has only been known to be observed in humans and not in mice. XCL1 induces it chemotactic function by binding to a chemokine receptor called XCR1. XCL1 is expressed on macrophages, fibroblasts, and specific lymphocytes. LTN, is found in two states: a monomer at 10 °C, LTN10, and a dimer at 40 °C, LTN40. Genomics XCL1's gene is found on the long arm of chromosome 1, located on cytogenetic band q24.2 as seen in the infobox. The encoding gene is made of 6,017 DNA bases to encode for the protein XCL1. This gene contains three exons and two introns as well as several transcription initiation sites. This gene encodes for the 114-amino acid protein called XCL1 which is similar to other chemokines except that it lacks the first and third cysteine characteristics. This means that XCL1 only contains one cysteine creating a disulfide bond instead of two or three like the other chemokines. The genetic differences between XCL1 and XCL2 are very small. Both proteins are from the same family containing the C motif structure containing one disulfide bond and have almost identical