TCL1A, also known as T-cell leukemia/lymphoma protein 1A, and TCL1B, also known as T-cell leukemia/lymphoma protein 1B, are both proteins in humans. These proteins are both notable for being implicated in the development of mature T cell leukemia, which chromosomal rearrangements bring the TCL1 gene in close proximity to the T-cell antigen receptor (TCR)-alpha or TCR-beta regulatory elements
The functions of TCL1A are to enhance the phosphorylation and activation of AKT1, AKT2, and AKT3, to promote the nuclear translocation of AKT 1, to enhance cell proliferation, and to stabilize mitochondrial membrane potential and promote cell survival. TCL1B acts as an Akt kinase co-activator and enhances the phosphorylation and activation of AKT1 and AKT2
The exact mechanisms by which TCL1A regulates tumor development in non-Hodgkin's lymphoma are not yet fully understood, but it is thought to play a role in the pathogenesis of other B-cell non-Hodgkin’s lymphoma malignancies. The mechanisms of TCL1B are thought to be analogous to the mechanisms of TCL1A.
TCL1A interacts with HIST3H2A (Histone H2A type 3), ATM (ATM Serine/Threonine Kinase), AKT1 (AKT Serine/Threonine Kinase 1), AKT2 (AKT Serine/Threonine Kinase 2), and (AKT Serine/Threonine Kinase 3). TCL1B also interacts with AKT, but furthermore, has interactions with MED1 (Mediator Complex Subunit 1) and MED28 ((Mediator Complex Subunit 28).
TCL1A structure is composed of a hydrophobic core surrounded by two 4-stranded β-sheets. One sheet is composed of shorter strands and the other of longer strands, both linked by a long and flexible loop between strands βD and βE.