Premium
Evidence of redox‐linked signaling for producing a giant signal complex
Author(s) -
Katano Yoshiaki,
Pu MeiYi,
Akhand Anwarul Azeim,
Hamaguchi Michinari,
Koga Yasuhiro,
Isobe KenIchi,
Fukuda Yoshihide,
Hayakawa Tetsuo,
Nakashima Izumi
Publication year - 1995
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240570309
Subject(s) - chemistry , phosphatidylinositol , signal transduction , cell surface receptor , biochemistry , biophysics , centrifugation , receptor , differential centrifugation , redox , ligand (biochemistry) , biology , organic chemistry
Abstract Previously we showed that a thiol‐reactive heavy metal, HgCl 2 , crosslinked multiple cell surface receptors through a ligand‐independent pathway, which produced massive aggregates of phosphotyrosine (PTYR)‐containing proteins beneath plasma membrane [Nakashima et al. (1994): J Immunol 152:1064–1071]. In this study we characterized these unique aggregates at the molecular level. The lysates in Brij 96 of thymocytes treated with HgCl 2 were separated into the supernatant and pellet fractions by simple centrifugation. Selected PTYR‐containing proteins and p56 lck appeared in the pellet fraction as quickly as 5 s after exposure to HgCl 2 , and were further increased in amount by 5 min. Although the mechanism of triggering these events was redox‐linked, the majority of proteins in the Brij 96‐insoluble aggregates were dissociated in SDS‐PAGE under nonreducing condition. This suggested that PTYR‐containing proteins and p56 lck themselves do not form dimer or polymer directly by thiol‐mediated bond. The pellet fraction was further found to include some other signal delivery elements, such as GTPase activating protein, phosphatidylinositol 3 kinase, and mitogen‐activated protein kinase. Finally, all of these signal elements and selected PTYR‐containing proteins were collected in the same fraction by the sucrose density gradient centrifugation. These results suggest a unique redox‐linked pathway of formation of a giant signal complex.