Update protein_database.md

TeachingMaterials/protein_database.md

@@ -15,6 +15,28 @@ Protein records are available mainly in text formats that include sequence entri
 ## Hands-on sessions on protein databases
 
 #### 1. [National Center for Biotechnology Information - NCBI](https://www.ncbi.nlm.nih.gov/)
+
+The NCBI interface
+    ###### Example proteins: 
+    * Tumor protein P53
+    
+    Human protein P53 is a tumor suppressor protein, the absence of which allows many cancers to proliferate.
+    
+    ###### Search method:
+    * Text/term search in [All fields] (simply type in your query)
+    * Limiting the search using [filters]
+        - Organism [ORGN]
+        - Source database
+        - Genetic component
+        - Bio-chemical/physical properties etc.
+    * Combining multiple search criteria by boolean AND, OR, NOT
+    * Browsing by taxonomy (right side of the screen)
+    
+    ###### Select ine record of your choice
+    * 
+        
+
+
 #### 2. [UniProt Knowledgebase](https://www.ebi.ac.uk/uniprot)
 - Swissprot and Trembl
 - Cross-reference