1bwn
From Proteopedia
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'''PH DOMAIN AND BTK MOTIF FROM BRUTON'S TYROSINE KINASE MUTANT E41K IN COMPLEX WITH INS(1,3,4,5)P4''' | '''PH DOMAIN AND BTK MOTIF FROM BRUTON'S TYROSINE KINASE MUTANT E41K IN COMPLEX WITH INS(1,3,4,5)P4''' | ||
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[[Category: Saraste, M.]] | [[Category: Saraste, M.]] | ||
[[Category: Surdo, P Lo.]] | [[Category: Surdo, P Lo.]] | ||
| - | [[Category: | + | [[Category: Btk motif]] |
| - | [[Category: | + | [[Category: Ph domain]] |
| - | + | [[Category: Transferase]] | |
| - | [[Category: | + | [[Category: Tyrosine-protein kinase]] |
| - | [[Category: | + | [[Category: X-linked agammaglobulinemia]] |
| - | [[Category: | + | [[Category: Zinc binding]] |
| - | [[Category: | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:02:47 2008'' |
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| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 09:02, 2 May 2008
PH DOMAIN AND BTK MOTIF FROM BRUTON'S TYROSINE KINASE MUTANT E41K IN COMPLEX WITH INS(1,3,4,5)P4
Overview
BACKGROUND: The activity of Bruton's tyrosine kinase (Btk) is important for the maturation of B cells. A variety of point mutations in this enzyme result in a severe human immunodeficiency known as X-linked agammaglobulinemia (XLA). Btk contains a pleckstrin-homology (PH) domain that specifically binds phosphatidylinositol 3,4,5-trisphosphate and, hence, responds to signalling via phosphatidylinositol 3-kinase. Point mutations in the PH domain might abolish membrane binding, preventing signalling via Btk. RESULTS: We have determined the crystal structures of the wild-type PH domain and a gain-of-function mutant E41K in complex with D-myo-inositol 1,3,4,5-tetra-kisphosphate (Ins (1,3,4,5)P4). The inositol Ins (1,3,4,5)P4 binds to a site that is similar to the inositol 1,4,5-trisphosphate binding site in the PH domain of phospholipase C-delta. A second Ins (1,3,4,5)P4 molecule is associated with the domain of the E41K mutant, suggesting a mechanism for its constitutive interaction with membrane. The affinities of Ins (1,3,4,5)P4 to the wild type (Kd = 40 nM), and several XLA-causing mutants have been measured using isothermal titration calorimetry. CONCLUSIONS: Our data provide an explanation for the specificity and high affinity of the interaction with phosphatidylinositol 3,4,5-trisphosphate and lead to a classification of the XLA mutations that reside in the Btk PH domain. Mis-sense mutations that do not simply destabilize the PH fold either directly affect the interaction with the phosphates of the lipid head group or change electrostatic properties of the lipid-binding site. One point mutation (Q127H) cannot be explained by these facts, suggesting that the PH domain of Btk carries an additional function such as interaction with a Galpha protein.
About this Structure
1BWN is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structure of the PH domain from Bruton's tyrosine kinase in complex with inositol 1,3,4,5-tetrakisphosphate., Baraldi E, Djinovic Carugo K, Hyvonen M, Surdo PL, Riley AM, Potter BV, O'Brien R, Ladbury JE, Saraste M, Structure. 1999 Apr 15;7(4):449-60. PMID:10196129 Page seeded by OCA on Fri May 2 12:02:47 2008
