Current database objects used in GO annotations include gene identifiers, protein identifiers and RNA identifiers. The type database object applied in an annotation is indicated in column 12 (for example: 'protein','gene_product','snRNA').
Because a single gene may encode a number of different products with different attributes, GO recommends using column 17, where possible, to indicate a particular gene product form (such as a protein identifier, protein isoform identifier).
If no further specificiation is possible in column 17 from the evidence available to the curator, then the Consortium suggests that the annotation object is associated with all GO terms applicable to any of its products. See the annotation file format guide for more information.