APRIL (a proliferation-inducing ligand) was identified in 1998 through database mining, and is a member of the TNF (tumor necrosis factor) family. APRIL gene is localized to human chromosome 17p13, contains six exons, and is alternatively transcribed to 1.8, 2.1, and 2.4 kb mRNA transcripts. APRIL protein is composed of a cytosolic domain of 28 amino acids, and a transmembrane region. It also contains an exoplasmic region, made up of a stalk and a TNF domain. It shares the highest similarity to BLyS (B lymphocyte stimulator) protein, ~30% sequence similarity in the TNF domain. It is synthesized as a type II transmembrane protein, and is proteolytically processed as a mature protein, which is a soluble and non-covalent trimer.
[1] Recombinant murine APRIL is a soluble 21.9 kDa protein, consisting of 192 amino acid residues.
APRIL, a member of the TNF superfamily, is expressed in monocytes, macrophages, certain transformed cell lines, certain cancers of colon, and lymphoid tissues. APRIL, along with another TNF family member, BAFF, compete for two receptors, TACI and BCMA. ARPIL has the ability to stimulate proliferation of various tumor cell lines including Jurkat T cells and MCF-7 carcinoma cells. Like BAFF, APRIL also stimulates the proliferation of B and T cells. The human APRIL gene codes for at least four alternatively spliced transcriptional variants, which give rise to different isoforms of the APRIL precursor protein. All isoforms can be cleaved by the protease, furin, to release a soluble C-terminal fragment, which comprises the TNF like receptor binding of the APRIL precursor. Recombinant murine APRIL is a soluble 21.9 kDa protein, consisting of 192 amino acid residues.