title: On the linkage of exoplasmatic freeze-fracture particles to phycobilisomes.
abstract: The thylakoids of the thermophilic cyanobacterium Mastigocladus laminosus were examined by freeze-fracture analysis. The expolasmatic (EF)-freeze-fracture particles are organized in rows, separated by 45 nm or more with a 12-nm center-tocenter spacing of neighboring particles. Phycobilisomes, associated to the outer thylakoid surfaces show a similar spacing pattern. Fractures exposing simultaneously phycobilisomes and EF-freeze-fracture particles on the same thylakoid show a direct alignment of both systems. Consequently the phycobilisomes are concluded to be associated peripherally on top of the EF-freeze-fracture particles in a 1:1 assembly pattern. The periodicity of the EF-freeze-fracture particles determines the arrangement of the phycobilisomes in the rows. The planar phycobilisome model of Mörschel et al. (1977) easily allows a successive arrangement of the phycobilisomes in a row, whereas with the staggered model developed by Bryant et al. (1979), only a cogged arrangement of neighboring phycobilisomes is possible.
authors.affiliation: Kari von Frisch-Strasse, Fachbereich Biologie der Philipps-Universität, D-3550, Marburg, Federal Republic of Germany.
authors.forename: E
authors.initials: E
authors.lastname: Mörschel
authors.forename: K
authors.initials: K
authors.lastname: Mühlethaler