NPH3RPT

NPH3RPT is a plant protein encoded by the NPH3RPT gene and is classified as part of the NPH3-related protein family involved in phototropism signaling. The gene has been identified in several angiosperms, with orthologs detected in both dicot and monocot species. The protein is predicted to be cytosolic and is thought to lack transmembrane segments, containing predicted coiled-coil regions that may mediate protein–protein interactions and a conserved C-terminal region of unknown function.

Expression studies show that NPH3RPT transcripts are enriched in early-development tissues such as seedlings, with notable expression in hypocotyls and roots. Some species report modest induction by light, suggesting regulation by photoreceptor signaling pathways.

Functionally, NPH3RPT is proposed to participate in blue-light signaling pathways that influence phototropic bending and growth orientation. It may act downstream of or in parallel with the better-characterized NPH3 protein. In several plant lines, loss- or reduction-of-function mutations produce mild to moderate changes in tropic responses, indicating a modulatory role within a broader signaling network rather than serving as a primary photoreceptor effector.

Interactions with other components include reported associations with NPH3 and with signaling kinases, supporting a role in a larger phototropic signaling complex. Evolutionarily, the gene is conserved across angiosperms, with multiple paralogs arising from duplication events that contribute to lineage-specific expression patterns.

Research status remains ongoing, and precise molecular mechanisms are not fully resolved. Further genetic, biochemical, and cell-biological studies are needed to define its exact contributions to light signaling and plant architecture.