Find the protein entry in RCSB Protein Data Base.
On the summary page you'll find the primary citation: the first article to identify this protein. This is the starting point for your literature review.
Make a note of the citation information - article title, author(s), and journal name, year, volume, and page numbers.
Note the PubMed ID which you'll use to locate the primary citation in Scopus.
Click [Read More & Search PubMed Abstracts] to read the entire abstract, which provides an overview of the article.
Note the Keywords section after the abstract. These keywords may be useful for locating revelant articles and other resources.