RESUMO
Tarzarotene-induced gene 3 (TIG3) and HRAS-like suppressor (HRASLS3) are members of the HREV107 family of class II tumor suppressors, which are down-regulated in various cancer cells. TIG3 and HRASLS3 also exhibit phospholipase activities. Both proteins share a common domain architecture with hydrophilic N-terminal and hydrophobic C-terminal regions. The hydrophobic C-terminal region is important for tumor suppression. However, the function of the hydrophilic N-terminal region remains elusive. To facilitate biochemical characterizations of TIG3 and HRASLS3, we expressed and purified the N-terminal regions of TIG3 and HRASLS3, designated TIG3 (1-134) and HRASLS3 (1-133), in a bacterial system. We found that the N-terminal regions of TIG3 and HRASLS3 have calcium-independent phospholipase A(2) activities. Limited proteolysis revealed that TIG3 (1-132) is a structural domain in the N-terminal region of TIG3. Our data suggest that the hydrophobic C-terminal regions might be crucial for cellular localization, while the hydrophilic N-terminal regions are sufficient for the enzymatic activity of both TIG3 and HRASLS3.
Assuntos
Bioquímica/métodos , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/isolamento & purificação , Receptores do Ácido Retinoico/química , Receptores do Ácido Retinoico/isolamento & purificação , Proteínas Supressoras de Tumor/química , Proteínas Supressoras de Tumor/isolamento & purificação , Sequência de Aminoácidos , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Dados de Sequência Molecular , Fosfolipases A2/metabolismo , Fosfolipases A2 Independentes de Cálcio , Estrutura Terciária de Proteína , Receptores do Ácido Retinoico/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Proteínas Supressoras de Tumor/metabolismoRESUMO
Transglutaminase 2 (TG2) is a calcium-dependent multifunctional protein associated with various human diseases. We determined the crystal structure of human TG2 in complex with adenosine triphosphate (ATP). The ATP molecule binds to the previously identified guanosine diphosphate (GDP) binding pocket but has different hydrogen bonds and ion interaction with protein. The four residues Arg476, Arg478, Val479 and Tyr583, all of which are involved in both ATP and GDP binding by hydrogen bonds, might play important roles in the stabilization of TG2 by ATP or GDP. However, Ser482 and Arg580, which are involved in GDP binding, do not form hydrogen bond with ATP. Additionally, we newly discovered an intramolecular disulfide bond between Cys230 and Cys370, which formation might regulate the enzymatic activity of TG2.