N-terminal amino acid sequence of a 28 kDa major serum high density lipoprotein of the rainbow trout Oncorhynchus mykiss.

As there are few data on primary structures of fish apolipoproteins (apo), we determined the N-terminal sequence of a 28 kDa major serum protein of rainbow trout, a possible homologue of apoAI protein in higher vertebrates. Rainbow trout serum was separated by two-dimensional electrophoresis. A spot of the 28 kDa protein (pl 5.45) was cut out and directly applied to a protein sequencer. We succeeded in sequencing 30 amino acids from the N-terminal. The sequence of the 28 kDa protein shared a high similarity with that of apoAI of Atlantic salmon (Salmo salar). These results showed that the 28 kDa protein is apoAI of rainbow trout.