Differential tolerance of 'pseudo-pathogenic' @entity6635 residues in XXXX -binding EGF domains of short fibulin proteins.

@entity462 @entity21380 @entity6635 @entity71786 @entity21379 @entity21378 @entity32879 @entity460 @entity1520 @entity1020
An @entity21380 ( @entity21380 ) mutation in the last canonical @entity460 -binding epidermal growth factor (cbEGF) domain of @entity21378 ( @entity21378 ) causes the rare @entity1020 , @entity21379 ( @entity21379 ). In cell culture studies, this mutation leads to inefficient @entity21378 secretion and higher intracellular steady state levels, likely due to @entity21378 @entity1520 bonding and/or protein folding problems. However, how the @entity21380 mutation actually causes @entity21379 is still largely unknown. Herein we tested whether the introduction of analogous, 'pseudo-pathogenic' @entity6635 mutations immediately after the bn @entity462 (bn+1) in other cbEGF domains also caused protein folding/secretion challenges. We found that introduction of @entity6635 mutations into each of the four other @entity21378 canonical cbEGF domains caused a significant reduction in protein secretion ranging from 2.7 to 56% of wild-type (WT) @entity21378 levels. Surprisingly, an @entity71786 mutation in the first canonical cbEGF domain of @entity21378 yielded the highest amount of secretion among the @entity21378 @entity6635 mutants, and its secretion defect could be rescued to near WT levels (95%) after growth temperature reduction. Interestingly, when similarly positioned @entity6635 mutations were introduced into any of the canonical cbEGF domains of the highly homologous protein, @entity32879 ( @entity32879 ), there was no effect on secretion. In an attempt to make @entity21378 tolerant of @entity6635 residues (like @entity32879 ), we genetically engineered @entity21378 to have a higher sequence homology with @entity32879 by deleting three insert regions present in @entity21378 , but not @entity32879 . However, deletion of one or more of these regions did not have a beneficial effect on @entity21380 @entity21378 secretion. Overall, these results demonstrate that the introduction of @entity6635 residues at the bn+1 position does not universally disrupt cbEGF domain folding and secretion, but that their effect is context dependent, and in this case, uniquely disrupt the folding of canonical cbEGF domains of @entity21378 , but not @entity32879 .
