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been confirmed in principle for sea urchin outer fibers by Yanagisawa, Hasegawa, and Mohri (1968) and, in addition, these workers have presented evidence that the terminal phosphate of ATP is transferred to the bound guanine nucleotide of the outer fibers during active flagellar beat, presumably as a result of dynein ATPase activity. A great deal has been learned over the last several decades about the chemistry of muscle contraction through detailed ultrastructural studies of the sarcomere during contraction, the fractionation of the sarcomere into its constituent proteins, a study of the properties of these proteins, the reconstitution of the natural form that these proteins take in the filaments of the sarcomere, and finally a comparison of the enzymatic properties of the myofibril with those of its constituent parts (cf . Huxley, 1969) . It is with this philosophy in mind that a detailed study of the cilium and its constituent proteins has been undertaken . This present report attempts to outline some of the basic enzymatic properties of the ciliary axoneme, i .e . the dynein tubulin complex without the presence of complicating membranexATPase . A subsequent report (R . Linck, manuscript in preparation) will describe the properties of dynein obtained from this same system, the gill cilia of Pecten irradians . Ciliary and flagellar axonemes have been fractionated into several well defined protein components . As in muscle, the proteins of these organelles correspond to enzymatic and structural elements, but their interactions are still quite uncertain . The ATPase dynein, identified as "arms" in the 9 + 2 structure (Gibbons, 1963), can be obtained in two enzymatically active forms. Cilia from Tetrahymena pyriformis yield both a 14S "monomer" and a 30S polymeric form (Gibbons and Rowe, 1965), while sea urchin flagella yield only the 14S particle (Gibbons, 1965 a) . The enzymology of the two forms of dynein has been studied in detail by Gibbons (1966) . Allen (1968) has recently presented evidence that the two arms of Tetrahymena cilia are structurally asymmetric, but it is still unclear whether the two enzymatic forms of dynein have different locations or are simply related as monomer and polymer, associating differently to form the unique arms . The protein of the outer fibers of cilia and flagella, tubulin (Mohri, 1968), has been shown to contain bound guanine nucleotides, occurring in a ratio of 1 mole of total guanosine dior triphosphate per 60,000 g (1 mole) of outer fiber tubulin in sea urchin flagella, or the same amount of guanine or guanosine in Tetrahymena or Pecten cilia (Stephens, Renaud, and Gibbons, 1967 ; Stephens and Linck, 1969) . These results have

SOME ENZYMATIC PROPERTIES OF AXONEMES FROM THE CILIA OF PECTEN IRRADIANS