Protein Sequence DatabasesPIR, SWISS-PROT and TREMBEL

Protein Sequence Databases

PIR, SWISS-PROT and TREMBEL

1. Introduction

Protein sequence databases are biological databases that store information about amino acid sequences of proteins, along with their functional, structural, and biochemical characteristics. Since proteins are the functional molecules of the cell, protein databases are essential for understanding gene expression, metabolism, enzymatic activity, signaling pathways, and evolution.

Protein sequence databases mainly contain data derived from translated nucleotide sequences and experimental protein studies.

2. Types of Protein Sequence Databases

Protein sequence databases are broadly classified into:

A. Primary Protein Databases

Contain original protein sequence data

Minimal or no manual annotation

B. Secondary Protein Databases

Derived from primary databases

Provide curated functional and structural information

C. Composite Protein Databases

Combine protein data from multiple sources

Reduce redundancy

3. Protein Information Resource (PIR)

Overview

Protein Information Resource (PIR) is one of the earliest protein sequence databases, developed to store and analyze protein sequences.

Maintained by

Georgetown University (USA)

In collaboration with NBRF (National Biomedical Research Foundation)

Data Content

Protein sequences

Functional information

Evolutionary relationships

Classification into protein families

Unique Features

Organized into protein superfamilies

Emphasis on evolutionary and functional classification

Non-redundant dataset

Advantages

High-quality annotations

Useful for comparative protein studies

Limitations

Smaller than newer databases

Less frequently updated compared to UniProt

4. SWISS-PROT Database

Overview

SWISS-PROT is a manually curated, high-quality protein sequence database known for its accuracy and reliability.

Maintained by

Swiss Institute of Bioinformatics (SIB)

European Bioinformatics Institute (EMBL-EBI)

Data Content

Amino acid sequences

Protein function

Enzyme activity

Post-translational modifications

Domain structure

Subcellular localization

Key Features

Manual curation by experts

Minimal redundancy

High annotation accuracy

Extensive cross-references

SWISS-PROT Entry Includes :

Accession number

Protein name

Organism

Function

Sequence length

Amino acid sequence

Advantages

Highly reliable

Preferred for functional studies

Limitations

Slow growth due to manual annotation

5. TrEMBL (Translated EMBL)

Overview

TrEMBL is a computer-annotated protein database that contains protein sequences translated from nucleotide sequence databases.

Maintained by

EMBL-EBI

Swiss Institute of Bioinformatics

Data Source

Translations of coding sequences from:

EMBL

GenBank

DDBJ

Key Features

Automatically annotated

Large and rapidly growing database

Supplement to SWISS-PROT

Advantages

Covers newly discovered proteins

Fast data availability

Limitations

Annotation may contain errors

Less reliable than SWISS-PROT

6. UniProt Knowledgebase (UniProtKB)

SWISS-PROT and TrEMBL together form the UniProt Knowledgebase (UniProtKB).

Components

UniProtKB/Swiss-Prot – reviewed, manually curated

UniProtKB/TrEMBL – unreviewed, automatically annotated

Purpose

Provide comprehensive protein sequence and functional information

Serve as a central protein knowledge hub

7. Comparison of PIR, SWISS-PROT, and TrEMBL

8. Applications of Protein Sequence Databases

Protein function prediction

Identification of conserved domains

Comparative protein analysis

Phylogenetic studies

Drug target identification

Enzyme characterization

9. Importance of Protein Sequence Databases

Link genes to protein function

Support proteomics research

Assist in metabolic pathway analysis

Aid in molecular evolution studies

Help in crop improvement and biotechnology

10. Conclusion

Protein sequence databases such as PIR, SWISS-PROT, and TrEMBL play a vital role in modern bioinformatics. While SWISS-PROT provides high-quality, manually curated protein data, TrEMBL ensures rapid availability of newly sequenced proteins. PIR contributes valuable evolutionary and functional classifications. Together, these databases support comprehensive protein research and biological discovery.

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