PMID: 9438128Jan 23, 1998Paper

Subcellular localization of the GTP-binding protein Rho in the sea urchin sperm

European Journal of Cell Biology
L E CastellanoJ García-Soto

Abstract

The Rho proteins are small G-proteins that belong to the Ras superfamily and play an essential role in the organization of the actin cytoskeleton. They are characteristically ADP-ribosylated by the exoenzyme C3 from Clostridium botulinum. Sea urchin sperm contain multiple small G proteins (28-24 kDa) whose identity and function are unknown. Here, we examined whether some of these proteins corresponded to the Rho subfamily. A sperm homogenate incubated with C3 and [32P]NAD revealed, by electrophoresis and autoradiography, a single radiolabeled band with a molecular mass of 25 kDa; this size was identical, under the same conditions, to that displayed by RhoA from human platelets. In flagellar fractions, the 25 kDa protein ADP-ribosylated by C3 localized in the cytosol and in the plasma membrane. In the sperm head, the 25 kDa protein was detected in a membrane preparation enriched in acrosomal and plasma membranes. Separation of these head membranes through a continuous density gradient revealed that both the 25 kDa protein [32P]ADP-ribosylated by C3 and actin had the same localization as bindin, the adhesive protein characteristic of the acrosome. An antibody against RhoB cross-reacted by immunoblotting with the 25 kDa protein an...Continue Reading

Related Concepts

Related Feeds

Botulism (ASM)

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium clostridium botulinum. Discover the latest research on botulism here.

Botulism

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium clostridium botulinum. Discover the latest research on botulism here.