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Updated: Jun 18, 2026

Quantitative Localization of a Golgi Protein by Imaging Its Center of Fluorescence Mass
Published on: August 10, 2017
C1 domain mediates CalDAGIII localization to the Golgi
Mingyu Zhang1, Hongyuan Xia, Xueqi Li
1Department of Cardiology, The 4th Affiliated Hospital of Harbin Medical University, 150001, Harbin, Peoples Republic of China.
Calcium and DAG diacylglycerol (DAG) signaling proteins, known as CalDAGs, are crucial for cell function. This study reveals that the C1 domain, not calcium-binding EF hands, dictates CalDAGIII localization and activity in B cells, suggesting DAG regulation.
Area of Science:
- Molecular Biology
- Cell Signaling
- Immunology
Background:
- CalDAGs (Calcium and DAG diacylglycerol-binding proteins) are guanyl exchange factors involved in cellular signaling.
- CalDAGIII specifically impacts B lymphocyte and endocrine cell functions, but its regulatory mechanisms are unclear.
Purpose of the Study:
- To investigate the subcellular localization of CalDAGIII.
- To determine the roles of its calcium-binding (EF hands) and DAG-binding (C1) domains in localization and function.
Main Methods:
- Subcellular localization studies of CalDAGIII.
- Analysis of domain-specific mutations in CalDAGIII.
- Assessment of p38 activation in B cells.
Main Results:
- CalDAGIII localizes to the Golgi apparatus.
- The C1 domain is essential for Golgi localization.
- The C1 domain, not EF hands, is critical for p38 activation in B cells.
Conclusions:
- CalDAGIII's localization and function in B cells are primarily regulated by its DAG-binding C1 domain.
- Calcium-binding EF hands do not appear to play a significant role in CalDAGIII's localization or p38 activation.
- These findings suggest DAG diacylglycerol is a key regulator of CalDAGIII activity.
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