PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1

Shuvalova, Ekaterina; Fortygina, Polina; Smirnova, Gulnur; Bal, Natialia; Alkalaeva, Elena; Kolosov, Peter

doi:10.3390/ijms27125310

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PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1

by

Ekaterina Shuvalova

¹

,

Polina Fortygina

²,

Gulnur Smirnova

^1,2

,

Natialia Bal

²

,

Elena Alkalaeva

¹

and

Peter Kolosov

^1,2,*

¹

Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia

²

Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 117485 Moscow, Russia

^*

Author to whom correspondence should be addressed.

Int. J. Mol. Sci. 2026, 27(12), 5310; https://doi.org/10.3390/ijms27125310

Submission received: 22 April 2026 / Revised: 3 June 2026 / Accepted: 10 June 2026 / Published: 11 June 2026

(This article belongs to the Special Issue Current Research on Structure and Functions of Ribosomal Proteins)

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Abstract

The scaffold protein RACK1 (Receptor for Activated C Kinase 1) integrates signaling and translation, acting as a core component of the 40S ribosomal subunit. It binds activated Protein Kinase C (PKC) isoforms and membrane receptors. We used an auxin-inducible degron (AID2) system in human HAP1 cells to selectively deplete the free (cytoplasmic) pool of RACK1. The engineered RACK1–mAID–mClover3 fusion was rapidly degraded in the cytoplasm upon addition of 5-phenyl-indole-3-acetic acid (5-Ph-IAA), while the ribosome-bound pool remained detectable in ribosomal fractions, indicating that ribosome association makes RACK1 relatively less accessible to AID2-mediated proteolysis. Upon activation of PKCβII with phorbol-12-myristate-13-acetate (PMA), imaging at defined time points revealed closely matched kinetics of PKCβII membrane recruitment and membrane-proximal enrichment of ribosome-bound RACK1, peaking at ~10 min. Our data support a model in which activated PKCβII engages ribosome-bound RACK1 at membrane-proximal sites, consistent with a diffusion–capture mechanism in which PKCβII first accumulates at the membrane and then captures ribosome-bound RACK1, thereby recruiting the translational machinery to sites of signal input for membrane-proximal translation. These findings provide new insights into the spatial organization of translation.

Keywords: RACK1; PKCβII; local translation; ribosome

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MDPI and ACS Style

Shuvalova, E.; Fortygina, P.; Smirnova, G.; Bal, N.; Alkalaeva, E.; Kolosov, P. PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1. Int. J. Mol. Sci. 2026, 27, 5310. https://doi.org/10.3390/ijms27125310

AMA Style

Shuvalova E, Fortygina P, Smirnova G, Bal N, Alkalaeva E, Kolosov P. PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1. International Journal of Molecular Sciences. 2026; 27(12):5310. https://doi.org/10.3390/ijms27125310

Chicago/Turabian Style

Shuvalova, Ekaterina, Polina Fortygina, Gulnur Smirnova, Natialia Bal, Elena Alkalaeva, and Peter Kolosov. 2026. "PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1" International Journal of Molecular Sciences 27, no. 12: 5310. https://doi.org/10.3390/ijms27125310

APA Style

Shuvalova, E., Fortygina, P., Smirnova, G., Bal, N., Alkalaeva, E., & Kolosov, P. (2026). PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1. International Journal of Molecular Sciences, 27(12), 5310. https://doi.org/10.3390/ijms27125310

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PKCβII Activation Promotes Membrane-Proximal Enrichment of Ribosome-Bound RACK1

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