In biology, a protein isoform is a version of a protein with some small differences, usually a splice variant or the product of some posttranslational modification. A good number of isoforms are formed because of presence of SNPs.

The discovery of isoforms explains the apparently small number of coding genes revealed in the human genome project: the ability to create catalytically different proteins from the same gene increases the diversity of the genome. Isoforms are readily described and discovered by microarray studies and cDNA libraries.

Glycoforms

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A glycoform is an isoform where different versions of a glycoprotein have different polysaccharides attached to them, by either posttranslational or cotranslational modifications.

Isoform | Proteïne isovorm