“…A first report on outer membrane proteins of a prochlorophyte is given in this study by comparing polypeptide profiles of isolated cell envelopes and Triton-insohible cell walls from Prochlorothrix hollandica analyzed by SDS-PAGE under the influence of ~-mercaptoethanol, heat and SDS. The major proteins of the outer membrane of Prochlorothrix hollandicn showed similar characteristics as those of the outer membranes from various cyanobacteria, The major polypeptides ( M r 56000 and 59000) were found to he in the relatively high molecular mass range from M r 49000 to 67000 as described for the cyanobacteria, Anacystis nidulans KM [21,22], Anacystis nidulans R-2, Synechococcus leopoliensis UTEX 625, Synechococcus sp. [23], Synechocystis sp.…”