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Alix, a novel mouse protein undergoing calcium-dependent interaction with the apoptosis-linked-gene 2 (ALG-2) protein
M Missotten1, A Nichols, K Rieger
1Serono Pharmaceutical Research Institute, 14 Chemin des Aulx, 1228 Plan les Ouates, Geneva, Switzerland.
Abstract:
ALG-2 is a EF hand calcium binding protein with sequence homologies to calmodulin. Vito et al have shown that ALG-2 expression is required for apoptosis following a number of death stimuli,1 although nothing is known about the effectors which underlie ALG-2 function. Here we have used ALG-2 as bait in a yeast two hybrid screen of a mouse brain cDNA library. We found that ALG-2 binds to itself and to a novel protein that we call ALG-2 interacting protein X, Alix. Using co-immunoprecipitation experiments, we confirmed ALG-2/ALG-2 binding and demonstrated that this interaction is calcium independent. ALG-2/Alix interaction was also validated by co-immunoprecipitation, but in this case, the binding was found to be strictly calcium dependent. Alix seems highly conserved throughout evolution since it shows significant homologies to a putative C. elegans protein (YNK-1) and to proteins of A. nidulans (PalA) and S. cerevisiae (BRO1). Alix is a potential regulator or downstream effector of ALG-2 action.
Insights
Apoptosis regulator ALG-2 binds to itself and a novel protein, Alix. This discovery sheds light on ALG-2
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Apoptosis is a crucial cellular process regulated by various proteins.
- ALG-2 (also known as ALG-2) is an EF-hand calcium-binding protein homologous to calmodulin.
- The specific effectors mediating ALG-2's role in apoptosis remain largely unknown.
Purpose of the Study:
- To identify novel proteins that interact with ALG-2.
- To elucidate the functional relationship between ALG-2 and its binding partners.
Main Methods:
- Yeast two-hybrid screening using ALG-2 as bait against a mouse brain cDNA library.
- Co-immunoprecipitation experiments to validate protein-protein interactions.
Main Results:
- ALG-2 was found to bind to itself (homodimerization) and to a novel protein, Alix (ALG-2 interacting protein X).
- ALG-2/ALG-2 binding is calcium-independent.
- ALG-2/Alix interaction is strictly calcium-dependent.
- Alix exhibits homology to conserved proteins across species (e.g., YNK-1, PalA, BRO1), suggesting functional importance.
Conclusions:
- Alix is identified as a novel binding partner of ALG-2.
- The calcium-dependent interaction between ALG-2 and Alix suggests a regulatory mechanism in cellular processes.
- Alix is a potential downstream effector or regulator of ALG-2's function in apoptosis.