A genomic clone encoding a cryptophyte phycoerythrin alpha-subunit. Evidence for three alpha-subunits and an N-terminal membrane transit sequence.

A genomic library of Chroomonas (Cryptophyceae) DNA has been constructed in lambda EMBL4. Using a synthetic oligomer as a hybridization probe, a clone containing a phycoerythrin alpha-subunit has been obtained and sequenced. The principal alpha 1- and alpha 2-subunits of the holoprotein have been partially sequenced by sequential Edman degradation and differ from the DNA derived sequence, providing evidence for at least 3 alpha-subunit genes. The nucleotide sequence of the alpha-subunit gene is GC rich and encodes an N-terminal extension which is putatively thylakoid-lumen directing.