Biomaterial Database

Characterization of valine transport in sea urchin eggs. 1984

D Allemand, and G De Renzis, and B Ciapa, and J P Girard, and P Payan

In unfertilized eggs, the mechanism of valine uptake can be summarized as follows. It is saturable over the external concentration of valine and insensitive to the presence of external sodium, depletion of cellular energy supplies and intracellular acidosis. The activation energy for the transport reaction (16.3 kcal/mol) is within the range of values reported for active transport of small molecules. In fertilized eggs, the total rate of valine uptake can be divided into two components: (i) a Na+-insensitive uptake which accounts for about 7% of total absorption as shown by studies in Na+-free medium seems to possess the same characteristics as in unfertilized eggs, (ii) a Na+-dependent transport of valine which constitutes the main entry is formed about 5 min after fertilization. It follows Michaelis-Menten kinetics characterized by 15-fold increase in Vmax with no change in Km. These two mechanisms have characteristics in common, such as their insensitivity to metabolic energy supply, their energy of activation and their ability to concentrate valine. The relationship between the establishment of the Na+-dependent valine uptake and the ionic events triggered by fertilization is discussed.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010063	Ovum	A mature haploid female germ cell extruded from the OVARY at OVULATION.	Egg,Egg, Unfertilized,Ova,Eggs, Unfertilized,Unfertilized Egg,Unfertilized Eggs
D005260	Female		Females
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001667	Binding, Competitive	The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.	Competitive Binding
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012617	Sea Urchins	Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.	Echinoidea,Sand-Dollar,Clypeasteroida,Sand Dollars,Clypeasteroidas,Dollar, Sand,Dollars, Sand,Echinoideas,Sand Dollar,Sand-Dollars,Sea Urchin,Urchin, Sea,Urchins, Sea
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23