Lymphocyte Phosphatase-Associated Phosphoprotein (LPAP) as a CD45 Protein Stability Regulator

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Natalia A. Kruglova¹, Dmitriy V. Mazurov², and Alexander V. Filatov^2,3,a*

¹Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia

²National Research Center Institute of Immunology, Federal Medical Biological Agency of Russia, 115522 Moscow, Russia

³Department of Immunology, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia

Received November 5, 2023; Revised January 14, 2024; Accepted January 16, 2024

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Lymphocyte phosphatase-associated phosphoprotein (LPAP) is a binding partner of the phosphatase CD45, but its function remains poorly understood. Its close interaction with CD45 suggests that LPAP may potentially regulate CD45, but direct biochemical evidence for this has not yet been obtained. We found that in the Jurkat lymphoid cells the levels of LPAP and CD45 proteins are interrelated and well correlated with each other. Knockout of LPAP leads to the decrease in the surface expression of CD45, while its overexpression, on the contrary, caused its increase. No such correlation was found in the non-lymphoid K562 cells. We hypothesize that LPAP regulates expression level of CD45 and thus can affect lymphocyte activation.

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KEY WORDS: LPAP, CD45, T cell receptor, lymphocyte activation

DOI: 10.1134/S0006297924050110

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