Protein phosphorylation during activation of surf clam oocytes

Growing Pollen Tubes Possess a Constitutive Alkaline Band in the Clear Zone and a Growth-dependent Acidic Tip

“…Key words: pollen tube growth • pH • proton flux • ratiometric ion imaging • vibrating probe D ESPITE considerable effort to measure and image cytosolic pH (pH c ), 1 a generalized understanding of the status and role of protons in cellular physiology remains elusive. Yet pH c plays a central role in the regulation of a number of cellular processes including modulation of enzyme activity (Guern et al, 1991), state of phosphorylation (Blowers and Trewavas, 1989), structure and activity of the cytoskeleton (Yonezawa et al, 1985;Suprenant, 1991;Andersland and Parthasarathy, 1993;Edmonds et al, 1995), endocytosis and exocytosis (Cosson et al, 1989;Gluck et al, 1982), and protein synthesis and cell division (Dube et al, 1991;Grandin et al, 1991). The importance of these processes allows the prediction that protons might be one of the most basic and effective common denominators to convey spatial and temporal information inside a living cell, and leads to the notion that modulation of pH c acts as a bona fide second messenger (Felle, 1989).…”