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Journal Article

Identification and characterization of a novel human plant pathogenesis-related protein that localizes to lipid-enriched microdomains in the Golgi complex

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http://pubman.mpdl.mpg.de/cone/persons/resource/persons78335

Lottspeich,  F.
Lottspeich, Friedrich / Protein Analysis, Max Planck Institute of Biochemistry, Max Planck Society;

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Citation

Eberle, H. B., Serrano, R. L., Füllekrug, J., Schlosser, A., Lehmann, W. D., Lottspeich, F., et al. (2002). Identification and characterization of a novel human plant pathogenesis-related protein that localizes to lipid-enriched microdomains in the Golgi complex. Journal of Cell Science, 115(4), 827-838.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-6FB6-0
Abstract
Group 1 of plant pathogenesis-related proteins (PR-1) and a variety of related mammalian proteins constitute a superfamily of proteins that share structural similarities. Little is known about their function, but all the family members identified to date are co-translationally translocated to the lumen of the endoplasmic reticulum and are secreted as soluble proteins or are targeted to vacuoles. Here we report the identification of a novel family member that localizes to the cytosolic site of the endomembrane system in mammalian cells. After detergent solubilization of isolated Golgi membranes, a 17 kDa protein was found associated with a low-density detergent-insoluble fraction. The amino-acid sequence, determined by microsequencing and molecular cloning, revealed a significant homology with the superfamily of PR-I proteins. Golgi- associated PR-1 protein (GAPR-1) showed a brefeldin-A-sensitive Golgi localization in immunofluorescence. Interestingly, the protein remained associated with the microdomain fraction in the presence of Brefeldin A. By mass spectrometry, GAPR-1 was shown to be myristoylated. Immunoprecipitation of GAPR- 1 from Golgi membranes resulted in the coimmunoprecipitation of caveolin-1, indicating a direct interaction between these two proteins. Myristoylation, together with protein-protein or electrostatic interactions at physiological pH owing to the highly basic pI of GAPR-1 (pI 9.4) could explain the strong membrane association of GAPR-1. Tissue screening revealed that GAPR-1 is not detectably expressed in liver, heart or adrenal glands. High expression was found in monocytes, leukocytes, lung, spleen and embryonic tissue. Consistent with the involvement of PR-1 proteins in the plant immune system, these data could indicate that GAPR-1 is involved in the immune system.