Related Experiment Videos
A novel short isoform of the D3 dopamine receptor generated by alternative splicing in the third cytoplasmic loop
C S Fishburn1, D Belleli, C David
1Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel.
Abstract:
The mouse D3 dopamine receptor has been cloned from olfactory tubercle cDNA using polymerase chain reaction and has been found to exist in two alternatively spliced forms. These two mRNA isoforms differ by the presence or absence of 63 base pairs (bp), which encode 21 amino acids in the putative third cytoplasmic loop of the receptor. The longer form corresponds to the previously reported rat D3 dopamine receptor, to which it bears sequence homology of 94%. Northern blot analysis shows the mouse D3 receptor to be most abundant in the olfactory tubercle. Expression studies show the novel short D3 isoform to bind dopaminergic ligands with a D3-like pharmacological profile. Polymerase chain reaction analysis on different mouse brain regions shows the long and short D3 receptors to be present in the same tissues, the longer form invariably being the predominant one. Analysis of the gene for the mouse D3 dopamine receptor shows that no separate exon encodes the 63-bp stretch and reveals the presence of a consensus sequence for an acceptor site at the 3' end of the 63-bp stretch. This suggests that an internal acceptor site in the exon coding for the distal part of the third cytoplasmic loop directs alternative splicing of the D3 dopamine receptor.
Insights
Researchers identified two forms of the mouse D3 dopamine receptor (a brain protein) generated by alternative splicing. The longer form is more common, but both bind to dopamine-like substances.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- The D3 dopamine receptor plays a role in various brain functions.
- Understanding receptor variants is crucial for neuroscience research.
- Previous studies focused on the rat D3 dopamine receptor.
Purpose of the Study:
- To clone and characterize the mouse D3 dopamine receptor.
- To investigate the existence and nature of alternative splicing in the mouse D3 receptor.
- To determine the distribution and binding properties of different mouse D3 receptor isoforms.
Main Methods:
- Polymerase chain reaction (PCR) was used to clone the mouse D3 dopamine receptor from olfactory tubercle cDNA.
- Northern blot analysis was performed to determine the abundance and tissue distribution of the receptor.
- Expression studies were conducted to assess the pharmacological profile of the different isoforms.
Main Results:
- Two alternatively spliced mRNA isoforms of the mouse D3 dopamine receptor were identified, differing by 63 base pairs (bp) encoding 21 amino acids.
- The longer isoform shares 94% sequence homology with the rat D3 dopamine receptor.
- The mouse D3 receptor is most abundant in the olfactory tubercle, with both isoforms present in various brain regions, the longer form being predominant.
- The novel short D3 isoform exhibits a D3-like pharmacological profile, binding to dopaminergic ligands.
- Gene analysis revealed no separate exon for the 63-bp stretch, suggesting alternative splicing is directed by an internal acceptor site.
Conclusions:
- Alternative splicing generates distinct mouse D3 dopamine receptor isoforms with conserved pharmacological properties.
- The findings provide insights into the molecular mechanisms regulating D3 dopamine receptor expression and function.
- This study contributes to a deeper understanding of dopamine receptor diversity in the brain.