Identification and Validation of ISG15 Target Proteins

Area of Science:

• Biochemistry
• Immunology
• Molecular Biology

Background:

• Interferon-stimulated gene 15 (ISG15) is an interferon-induced ubiquitin-like protein (Ubl) with known antiviral properties.
• The conjugation machinery for ISG15 involves E1 (Ube1L), E2 (UbcH8), and E3 (Herc5) enzymes, all upregulated by Type 1 interferon signaling.

Purpose of the Study:

• To provide an overview of the methods used for identifying ISG15 target proteins.
• To discuss the validation strategies for these identified targets.
• To explore the characterized biochemical effects of ISG15 conjugation on its target proteins.

Main Methods:

• Proteomics studies were employed to identify cellular proteins conjugated to ISG15.
• Target validation approaches were reviewed.
• Biochemical analyses of ISG15-conjugated proteins were discussed.

Main Results:

• Over 300 cellular proteins were identified as ISG15 targets through combined proteomics efforts.
• Identified targets encompass both constitutively expressed proteins and approximately 15 interferon-induced proteins.
• The biochemical consequences of ISG15 conjugation remain characterized for a limited number of targets.

Conclusions:

• ISG15 conjugation targets a vast array of cellular proteins, highlighting its significant role in cellular processes and antiviral responses.
• Further research is needed to fully elucidate the functional impact of ISG15 conjugation on its diverse protein targets.