. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 150 G. T. BAXTER AND D. E. MORSE larval Haliotis refescens •. 1985)—as in marine turbellaria (Ehlers am: : '78)—paddle cilia are found only on sense reflecting, presumably, a unique speciali/atio 'S-gd electrophoresis confirmed the substanr. ion of the larval cilia (Baxter, 1991); a domr rotein with molecular mass identical to that of i iubulin was found in the cilia prepa- ration, whereas this was only a minor constituent of the proteins from the whole larvae. Lvsine receptors The purified cilia exhibit specific and saturab
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 150 G. T. BAXTER AND D. E. MORSE larval Haliotis refescens •. 1985)—as in marine turbellaria (Ehlers am: : '78)—paddle cilia are found only on sense reflecting, presumably, a unique speciali/atio 'S-gd electrophoresis confirmed the substanr. ion of the larval cilia (Baxter, 1991); a domr rotein with molecular mass identical to that of i iubulin was found in the cilia prepa- ration, whereas this was only a minor constituent of the proteins from the whole larvae. Lvsine receptors The purified cilia exhibit specific and saturable binding of [3H]-L-lysine that reaches equilibrium within 15 min at 2°C (Baxter, 1991). Scatchard analysis of the specific equilibrium binding (Fig. 2) formally resolves a high af- finity binding site (K<j 10 nAf). The maximal binding (Bmax) of lysine is on the order of 10 femtomoles/jug cilia protein at the high affinity site and ca. 100 femtomoles/^g protein at the low affinity site. Although exhibiting some variation from one preparation of cilia to another, these binding parameters proved highly reproducible within each preparation. The presence or absence of sodium had no significant effect on these parameters for lysine binding (Baxter, 1991). The abilities of the unlabeled facilitating diamino acids L-«,j8-diaminopropionic acid (DAPA), L-lysine and L- ornithine to compete for the specific binding of [3H]-L- lysine to the cilia are correlated with the activities of these compounds as facilitators of larval metamorphosis (Fig. 3). The rank order of binding strength and biological ef- fectiveness is DAPA > L-lysine > ornithine. 6x10-5. 100 150 200 ie Bound (fmoles/ug protein) Figure 2. Binding : I -Ivsine to cilia purified from Haliotis larvae. Scatchard analysis specific binding data. Data were analyzed with the compui. assisted non-linear curve fitting programs EBDA/LIGAND (McPherson. i')NM: each point represents the mean of three determinati
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
