Guanylate, unique to dried shiitake mushrooms, thickens other ingredients' umami (Glutamate). In other words, using dried shiitake mushrooms or shiitake powder in your cooking will make it taste even better than usual.

Here are three major academic papers that have been written about this.

1) Molecular mechanism of the allosteric enhancement of the umami taste sensation
Ole G. Mouritsen, Himanshu Khandelia, 2012
https://febs.onlinelibrary.wiley.com/doi/full/10.1111/j.1742-4658.2012.08690.x

When Glutamate enters the umami receptor, we sense umami.
Furthermore, Guanylate (the umami component of dried shiitake mushrooms) enters the receptor, closing the receptor's mouth and making us feel umami longer and stronger.

The following text is a clear summary of this paper by ChatGPT.

GMP (Guanylate, an umami component found in dried shiitake mushrooms) is a substance that plays an important role in the function of taste receptors. In particular, GMP exhibits intriguing effects on receptors involved in the umami taste. This research investigates how GMP affects the function of umami receptors.

First, researchers predicted the structure of the umami receptor. Then, using this structure, they conducted simulations with and without the presence of glutamate, an umami component. Furthermore, they performed simulations in combination with GMP.

As a result of the simulations, it was shown that GMP plays a crucial role in the function of umami receptors. Specific parts of the receptor bind strongly with GMP, which activates the receptor. These findings are consistent with the data obtained from experiments.

GMP is a key substance for experiencing umami and has been shown to play a role in enhancing the function of umami receptors. By applying this research, it may be possible to find ways to make food taste even better.

2) Flavor potentiators
Joseph A. Maga &Shizuko Yamaguchi, 2009
https://www.tandfonline.com/doi/abs/10.1080/10408398309527364

This paper provides a comprehensive introduction to the synergistic effects of umami.

"An even more dramatic synergistic effect has been shown for MSG-GMP combinations, where a 30-fold increase in flavor intensity has been reported when equal amounts of MSG and GMP were utilized.
These data would indicate that at their optimum effectiveness MSG-GMP combinations are approximately four times more synergistically potent than MSG-IMP."

3) Taste and Flavor Enhancement using Natural Ingredients: The Prediction and Optimization of Umami Taste in Real Food Systems
Lisa Methven, Maria Dermiki, Chutipapha Suwankanit, Orla B. Kennedy, Donald S. Mottram, 2014
https://www.sciencedirect.com/science/article/pii/B9780123985491000891

This paper is a study that looked for effective natural ingredients to enhance the umami flavor of cooked minced meat products.

"Combinations of soy sauce with either mycoprotein derivative, shiitake extract, or concentrated tomato extract led to maximized umami taste in the meat."

This paper explores methods for enhancing the taste and flavor of food using natural ingredients. The study examines how various natural ingredients can be added to minced meat products, including shiitake mushroom extract, yeast extract, mycoprotein extract, miso, soy sauce, and tomato puree, to increase their umami taste.
Results showed that adding these ingredients to the meat products enhanced their umami and salt perception, with mycoprotein, shiitake mushroom, concentrated tomato extract, and soy sauce being particularly effective.
The study suggests that using natural ingredients can provide more enjoyable food options for older individuals or those with taste disorders.