There is no list to my knowledge. Most of us look at the order of ingredients. The higher up on the list, the more of that ingredient.
If the protein is half way down the list of 23 ingredients, there is some but probably not a really high amount. If it is in the first 5 ingredients, there is quite a bit. If it is near the bottom, then I wouldn't even worry about it.
I would also look to see how many different proteins are being used. A product with 3 different proteins might be significant. Some of the marine protein products tend toward the multiples.
Remember, ingredients that start with Hydrolized are most likely protein.
3b spirals, fine texture, normal porosity, dense
Deva Low Poo
Suave Naturals Coconut for detangling
Renpure Organics conditioner/leave-in
Curl Junkie Stuff
Nothing lasts, nothing is finished, and nothing is perfect. -wabi-sabi