A famous protein-bound polysaccharide (PSK) contains 38% protein and polysaccharide (Sakami and Takeda, 1998). However, it is unfair to conclude as protein and polysaccharide always bind together unless you undergo deproteinization etc . Mushrooms are low in calories (carbs) with meat-like taste, I would say in general protein is higher for fruit bodies.

Mushrooms have higher levels of proteins and dietary fiber. like explained above by Wan Abd Al Qadr Imad Wan Mohtar. The polysaccharides in mushrooms are not readily soluble and this makes them healthier foods. The quality of proteins in Mushrooms is very high and comparable to the quality of proteins from animal sources. This is because of their high level content of the essential amino acids. A person can get the recommended dietary alloance of the essential amino acids from just a single serving a day. I am sure this will give you some idea.

Thanks