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Alternative mRNA forms and open reading frames of the max gene
I Västrik1, P J Koskinen, R Alitalo
1Department of Virology, University of Helsinki, Finland.
Oncogene
|February 1, 1993
Summary
The max gene produces multiple mRNA forms through alternative splicing, leading to distinct Max proteins. These forms are regulated by cell density and medium acidity, suggesting complex functional roles.
Area of Science:
- Molecular Biology
- Gene Expression Regulation
Background:
- The MAX gene encodes a crucial heterodimeric partner for Myc.
- An alternative splice variant, delta max mRNA, has been identified with an internal exon causing translational termination.
Purpose of the Study:
- To investigate the expression of diverse human MAX mRNA splice variants.
- To characterize the proteins encoded by these splice variants and their functional implications.
Main Methods:
- Northern blotting analysis was employed to study human MAX mRNA expression.
- Sequence analysis was performed on identified mRNA forms.
Main Results:
- Four additional MAX mRNA bands, besides the major 2.3-kb form, were detected, indicating differential splicing.
- These variants contain three open reading frames, predicting Max, delta Max, and a novel protein resembling delta Max.
- The novel 3.5-kb mRNA form, though minor in proliferating cells, increased under high cell density or acidic conditions.
- The protein from the 3.5-kb mRNA enhanced transformed foci in a ras-myc co-transformation assay, similar to delta Max.
Conclusions:
- The MAX gene undergoes complex alternative splicing, generating multiple mRNA forms.
- These splice variants encode functionally distinct Max proteins.
- Differential expression of MAX mRNA forms is influenced by cellular environment, suggesting regulatory roles in cell transformation.