# Functions and Synthesis of Abscisic Acid (ABA) in Humans—Insights from Computational Approaches

## TL;DR

This paper explores the presence and potential roles of abscisic acid, a plant hormone, in the human body using computational methods.

## Contribution

The paper proposes a novel ABA synthesis pathway in humans that bypasses carotenoids and identifies potential ABA-binding proteins linked to cancer and diabetes.

## Key findings

- Human proteins with ABA-binding signatures are linked to cancer and diabetes.
- ABA synthesis in humans may occur via farnesyl pyrophosphate, similar to fungi.
- Evidence suggests ABA is present in humans, though its source is unclear.

## Abstract

Abscisic acid (ABA) is a “classical” plant hormone and is key to many plant responses, notably seed germination, transpiration and defence. It is becoming increasingly clear that ABA acts not just through the canonical PYL/PYR/RCAR receptors but also through other proteins that can interact specifically with ABA. Here we use genomic and transcriptomic resources to show that the human proteome also contains proteins with specific ABA-binding signatures and that some of these potential ABA-binding proteins may have roles in cancer and diabetes. In addition, there is evidence for the presence of ABA in humans; however, the source of it remains somewhat inconclusive. Here we propose an ABA synthesis pathway that, much like in fungi, does not include carotenoids but proceeds via farnesyl pyrophosphate. In summary, we review the current status of ABA research in Homo sapiens and propose avenues that might lead to novel insights into the synthesis and biological roles of this ancient hormone, e.g., in obesity and inflammation.