In vivo threonine phosphorylation of immunoglobulin binding protein (BiP) maps to its protein binding domain
AUTOR(ES)
Gaut, James R.
FONTE
Cell Stress Society International
RESUMO
lmmunoglobin binding protein (BiP) molecules exist as both monomers and oligomers and phosphorylated BiP is restricted to the oligomeric pool. Modified BiP is not bound to proteins such as immunoglobulin heavy chain and consequently, may constitute an inactive form. Unlike earlier analysis of mammalian BiP isolated by two-dimensional gel electrophoresis, results here demonstrated that immunoprecipitated BiP displayed predominantly threonine phosphorylation with only a trace of detectable phosphoserine. Like other Hsp70 family members, BiP is comprised of three domains: an amino terminal domain which binds nucleotide, an 18 kilodalton domain which binds peptide, and a carboxyl terminal variable domain of unknown function. Cyanogen bromide cleavage and enzymatic digestion experiments mapped threonine phosphorylation to a site within a 47 amino acid sequence of the peptide binding domain which contains seven threonine residues. Partial proteinase K digestion in the presence of ATP independently verified that the in vivo phosphorylation site of mammalian (BiP) is located within the peptide binding domain. Furthermore, phosphorylation did not impede BiPs ATP-induced conformational change. Thus, the peptide binding domain of BiP is phosphorylated on threonine residue(s) mapping to not more than two tryptic fragments within the peptide binding domain. This location on the molecule could explain why phosphorylated BiP is not detected bound to proteins in vivo.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=313004Documentos Relacionados
- Inhibition of endoplasmic reticulum (ER)-to-Golgi transport induces relocalization of binding protein (BiP) within the ER to form the BiP bodies.
- Impaired Secretion of a Hydrophobic Cutinase by Saccharomyces cerevisiae Correlates with an Increased Association with Immunoglobulin Heavy-Chain Binding Protein (BiP)
- Location of the internal ribosome entry site in the 5' non-coding region of the immunoglobulin heavy-chain binding protein (BiP) mRNA: evidence for specific RNA-protein interactions.
- Dependence of Endoplasmic Reticulum-associated Degradation on the Peptide Binding Domain and Concentration of BiP
- Stable Binding of ATF6 to BiP in the Endoplasmic Reticulum Stress Response