RECEPTOR HETEROGENEITY AND SUBTYPES
Much of the sequence variation that accounts for receptor diversity arises
• from alternative splicing
a single gene can give rise to more than one receptor isoform.  After transmlation from genomic DNA, the mRNA normally contains non-coding regions (introns) that are excised by mRNA splicing before the message is translated into protein.  Depending on the location of the splice sites, splicing can result in insertion or deletion of one or more of the mRNA coding regions, giving rise to long or short forms of the protein
• from mRNA editing
From mischievous substitution of one base in the mRNAfor another; different receptors are produced from the same gene
2003-2004