The isoelectric point, a key to understanding a variety of biochemical problems: a minireview.

We address the importance of the isoelectric point (IEP) of proteins and membrane components such as phospholipids for our understanding and interpretation of isoforms and opposite charge interactions in the formation of complexes. Five examples drawn from the literature are newly approached from the IEP point of view to clarify general principles.

Organ-related distribution of phospholemman in the spiny dogfish Squalus acanthias.

The distribution of phospholemman among nine different organs of the spiny dogfish (Squalus acanthias) has been determined on the basis of Western blotting of microsomal material. Only rectal gland (100%), brain (43%), heart (18%), and kidney (19%) (abundancies as percent of the concentration in rectal gland) contained the protein, but not gill and colon. The relative abundance in the brain makes this organ a preferential test system for phospholemman in fishes that lack a rectal gland like teleosts.