They are unique among the photosynthetic pigments in that they are bonded to certain water-soluble proteins, known as phycobiliproteins.

The first proteins to be purified are water-soluble proteins.

Albumin is a highly water-soluble protein with considerable structural stability.

Some water-soluble proteins associate with lipid bilayers irreversibly and can form transmembrane alpha-helical or beta-barrel channels.

Typical water-soluble proteins have no exposed nonpolar residues or any other hydrophobic anchors.

Some water-soluble proteins and peptides can also form transmembrane channels.

Crystallins are water-soluble proteins that compose over 90% of the protein within the lens.

It is called a "domain" because an alpha-helix in a membrane can fold independently from the rest of the protein, similar to domains of water-soluble proteins.

When flour is mixed with water, the water-soluble proteins dissolve, leaving the glutenin and gliadin to form the structure of the resulting bread.

A number of water-soluble proteins can bind to the bilayer surface transiently or under specific conditions.