Annotation is the process of assigning a term to a gene or gene product, usually by reading papers and extracting the information. When you have isolated an informative phrase or word in some text, find the corresponding GO term for the concept. In some cases, the term used in a paper may not be the name used by the GO term, so it can be helpful to search the synonyms and definitions of a term, or to search for a key word.
What is the GO term used to describe the synthesis of glucose?
What GO term would you use to annotate a protein involved in the control of the cell cycle?
The GO consortium annotation guidelines contain comprehensive guidelines on the procedure of annotation; the salient points for the purposes of this exercise are listed below.
The most important thing to remember is that GO is interested in the normal activity of a gene product: where it acts, what its functions are and what processes it contributes towards.
Here are two text snippets; read them and try to pick out some GO terms which describe the gene products.
"Mutants with defects in RNA binding protein (RBP) are defective in cell growth and differentiation. An example RBP that regulates development is provided by the Bruno protein and its role as a translational repressor of oskar mRNA. In Drosophila, oskar is required for formation of germ cells and positioning of the posterior of the embryo."
Which GO terms would you annotate RBP with?
"Using microarray analysis, we identified RERG (ras-related and estrogen-regulated growth inhibitor). Like Ras, RERG protein exhibited intrinsic GDP/GTP binding and GTP hydrolysis activity. Unlike Ras proteins, RERG lacks a known recognition site for COOH-terminal prenylation and was localized primarily in the cytoplasm."
What GO terms would you assign to RERG?