ASSOCIATION OF A MYOSIN MOTOR WITH MEMBRANE-BOUNDED PIGMENT GRANULES IN FRESHWATER SHRIMP CHROMATOPHORES: EVIDENCE FROM THE NITELLA ACTIN-CABLE ASSAY

Autor(es)

McNamara, John Campbell ^[1] ; Boyle, Robert Tew ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, BR-14040901 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF CRUSTACEAN BIOLOGY; v. 29, n. 3, p. 387-392, AUG 2009.
• Citações Web of Science: 1

Resumo

We have adapted an actin-mosin motility assay to examine the interactions in vitro between actin cables isolated from the giant internodal cells of the freshwater alga, Nitella, and pigment granules extracted from red ovarian chromatophores of the freshwater palaemonid shrimp, Macrobrachium olfersi. The chromatophore pigment mass consists of large (0.5-1.0-mu m diameter) membrane-bounded granules, and small (140-nm diameter), a membranous granules, both structurally continuous with the abundant smooth endoplasmic reticulum. Our previous immunocytochemical studies show a myosin motor to be stably associated with the pigment mass; however, to which granule type or membrane the myosin motor is attached is unclear. Here, we show that sodium vanadate, a myosin ATPase inhibitor, markedly increases the affinity of isolated, large, membrane-bounded granules for Nitella actin cables to which they become permanently attached. This interaction does not occur in granule preparations containing ATP with uninhibited, active myosin without vanadate. We propose that a stable state of elevated affinity is established between the granule-located myosin motor and the Nitella actin cables, resulting from a vanadate-inhibited acto-myosin-ADP complex. This finding provides further evidence for a myosin motor positioned on the surface of the membrane-bounded pigment granules in shrimp ovarian chromatophores. (AU)

• Processo FAPESP: 00/04588-2 - Um estudo da transdução de sinal e do mecanismo de translocação pigmentar nos cromatossomos ovarianos do camarão Macrobrachium olfersii (Crustacea, Decapoda)
• Beneficiário: John Campbell McNamara
• Modalidade de apoio: Auxílio à Pesquisa - Regular