There are genetic methods for studying proteins, methods for detecting proteins, methods for isolating and purifying proteins and other methods for characterizing the structure and function of proteins, often requiring that the protein first be purified.
Genetic methods
conceptual translation- many proteins are never directly sequenced, but their sequence of amino acids is known by "conceptual translation" of a known mRNA sequence. See Genetic code.
site-directed mutagenesis allows new variants of proteins to be produced and tested for how structural changes alter protein function.
evolutionary; analysis of sequence changes in different species using software such as BLAST.
Proteins that are involved in human diseases can be identified by matching alleles to disease and other phenotypes using methods such as calculation of LOD scores.