1978/06/01 by Robert D. Allen, Nina S. Allen · 3 citations
Biochemistry, Genetics and Molecular Biology · #Protist diversity and phylogeny #Hemoglobin structure and function
paper · doi:10.1146/annurev.bb.07.060178.002345
openalex publication_date 1978/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
The study of motility and its molecular basis has received an important impetus from the discovery that the contractile protein actin is present in cells from organ isms of four of the five kingdoms (90), and bacterial elongation factor Tu from Escherichi a coli shares many but not all properties of actin (95). Myosin has been found in animals, protists, and fungi (90), but not yet in bacteria. The inconclusive evidence for myosin in plant cells is discussed in another review (8). Progress in motility research has been rapid and has been stimulated by recent reviews, which have focused on the broad perspective of the biochemistry of con tractile proteins (90) and on the range of possible control systems in motility (52). The present review and the one to follow (8) are more restricted in scope and represent an attempt to integrate the cellular and biophysical aspects of one type of motility with the emerging biochemical information. Although contraction in muscle is a reversible deformation attributable to cyclic movement of the myosin heads of thick filaments (56, 90), streaming is an irreversi ble deformation of whole cytoplasm that is apparently dependent upon the activity of similar contractile proteins. The complex relationship between the phenomena of contractility and of streaming in large, free-living amoebae is explored in depth in this review. Amoeboid movement is a fundamental cellular process of wide distribution in which cytoplasm streams within pseudopodia. Observers have described the process in many types of cells and have debated the merits of hypothetical mechanisms since the time of Dujardin (34), The review of DeBruyn (33) discusses the early literature and the development of the ectoplasmic contraction theory in the 19208 out of the descriptive studies of Pant in (83) and Mast (71), The ectoplasmic contrac tion theory was influential up to the early 1960s because of its logical simplicity and because no experiments had been designed to test it critically.