Functional domains of the human splicing factor ASF/SF2

Area of Science:

• Molecular Biology
• RNA Splicing
• Protein Function

Background:

• Alternative splicing is a key regulatory mechanism in gene expression.
• The splicing factor ASF/SF2 (also known as SF3A1) plays dual roles in splicing.
• ASF/SF2 belongs to a protein family characterized by RNA binding domains (RBDs) and arginine-serine rich (RS) regions.

Purpose of the Study:

• To functionally analyze the human splicing factor ASF/SF2.
• To identify regions critical for ASF/SF2's essential splicing and alternative splice site selection activities.
• To elucidate the role of RBDs and RS regions in ASF/SF2 function.

Main Methods:

• In vitro splicing assays.
• Analysis of deletion and substitution mutants of ASF/SF2.
• Investigation of protein isoforms and their effect on splicing.

Main Results:

• ASF/SF2 exhibits essential splicing and splice site switching activities.
• Two distinct RNA binding domains (RBDs) are essential for ASF/SF2 activity, with optimal RNA binding requiring both.
• The RS region is not essential for splice site switching but affects ASF/SF2's role as an essential splicing factor.
• Inactive ASF/SF2 isoforms can act as splicing repressors.

Conclusions:

• ASF/SF2's dual functions are mediated by distinct protein regions.
• Both RBDs are critical for ASF/SF2's essential splicing and RNA binding capabilities.
• The RS region's role is more nuanced, impacting essential splicing but not splice site switching.