Migration of the guinea pig sperm membrane protein PH-20 from one localized surface domain to another does not occur by a simple diffusion-trapping mechanism

Dev Biol. 1991 Mar;144(1):189-98. doi: 10.1016/0012-1606(91)90490-t.

Abstract

The redistribution of membrane proteins on the surface of cells is a prevalent feature of differentiation in a variety of cells. In most cases the mechanism responsible for such redistribution is poorly understood. Two potential mechanisms for the redistribution of surface proteins are: (1) passive diffusion coupled with trapping, and (2) active translocation. We have studied the process of membrane protein redistribution for the PH-20 protein of guinea pig sperm, a surface protein required for sperm binding to the egg zona pellucida (P. Primakoff, H. Hyatt, and D. G. Myles (1985). J. Cell Biol. 101, 2239-2244). PH-20 protein is localized to the posterior head plasma menbrane of the mature sperm cell. Following the exocytotic acrosome reaction, PH-20 protein moves into the newly incorporated inner acrosomal membrane (IAM), placing it in a position favorable for a role in binding sperm to the egg zona pellucida (D. G. Myles, and P. Primakoff (1984), J. Cell Biol. 99, 1634-1641). To analyze the mechanistic basis for this protein migration, we have used fluorescence microscopy and digital image processing to characterize PH-20 protein migration in individual cells. PH-20 protein was observed to move against a concentration gradient in the posterior head plasma membrane. This result argues strongly against a model of passive diffusion followed by trapping in the IAM, and instead suggests that an active process serves to concentrate PH-20 protein toward the boundary separating the posterior head and IAM regions. A transient gradient of PH-20 concentration observed in the IAM suggests that once PH-20 protein reaches the IAM, it is freely diffusing. Additionally, we observed that migration of PH-20 protein was calcium dependent.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acrosome / ultrastructure*
  • Animals
  • Calcimycin / pharmacology
  • Calcium / physiology
  • Cell Adhesion Molecules / metabolism*
  • Cell Compartmentation
  • Cell Membrane / ultrastructure
  • Diffusion
  • Exocytosis
  • Guinea Pigs
  • Hyaluronoglucosaminidase
  • Male
  • Membrane Proteins / metabolism*
  • Spermatozoa / physiology
  • Spermatozoa / ultrastructure*

Substances

  • Cell Adhesion Molecules
  • Membrane Proteins
  • Calcimycin
  • Hyaluronoglucosaminidase
  • hyaluronidase PH-20
  • Calcium