Biomaterial Database

Characterization of the lysosomal cystine transport system in mouse L-929 fibroblasts. 1990

A A Greene, and E G Marcusson, and G P Morell, and J A Schneider

Department of Pediatrics, University of California, San Diego, La Jolla 92093.

We characterize here a lysosomal cystine transporter in mouse L-929 fibroblasts. Granular fractions from cells preloaded with cystine demonstrated countertransport that showed no dependence on Na+ or K+. The Michaelis constant for infinite-trans influx was 0.27 +/- 0.06 mM (n = 3), and a nonsaturable component of cystine entry was observed with Kd = 0.8-1.8 nmol of cystine.min-1.unit of hexosaminidase-1.mM-1. We found no evidence that cystine was also carried on any of the other known lysosomal amino acid transporters. Over 50 analogs were tested for their ability to inhibit countertransport. The inhibition constants are reported for selenocystine, cystathionine, selenomethionine, and leucine. Significant requirements for recognition by the transporter were the presence of amino groups, L configuration, and a chain length not greater than eight atoms. A net positive or negative charge was not required. Some di- as well as tetrapolar amino acids were recognized. We have surmised that the binding site has polar and apolar domains, the latter being large enough to accommodate branching on C-3 and the substitution of selenium or carbon in place of sulfur.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007739	L Cells	A cultured line of C3H mouse FIBROBLASTS that do not adhere to one another and do not express CADHERINS.	Earle's Strain L Cells,L Cell Line,L Cells (Cell Line),L-Cell Line,L-Cells,L-Cells, Cell Line,L929 Cell Line,L929 Cells,NCTC Clone 929 Cells,NCTC Clone 929 of Strain L Cells,Strain L Cells,Cell Line L-Cell,Cell Line L-Cells,Cell Line, L,Cell Line, L929,Cell Lines, L,Cell, L,Cell, L (Cell Line),Cell, L929,Cell, Strain L,Cells, L,Cells, L (Cell Line),Cells, L929,Cells, Strain L,L Cell,L Cell (Cell Line),L Cell Lines,L Cell, Strain,L Cells, Cell Line,L Cells, Strain,L-Cell,L-Cell Lines,L-Cell, Cell Line,L929 Cell,Strain L Cell
D008247	Lysosomes	A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured or undergoes MEMBRANE FUSION. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed).	Autolysosome,Autolysosomes,Lysosome
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D008968	Molecular Conformation	The characteristic three-dimensional shape of a molecule.	Molecular Configuration,3D Molecular Structure,Configuration, Molecular,Molecular Structure, Three Dimensional,Three Dimensional Molecular Structure,3D Molecular Structures,Configurations, Molecular,Conformation, Molecular,Conformations, Molecular,Molecular Configurations,Molecular Conformations,Molecular Structure, 3D,Molecular Structures, 3D,Structure, 3D Molecular,Structures, 3D Molecular
D003196	Computer Graphics	The process of pictorial communication, between human and computers, in which the computer input and output have the form of charts, drawings, or other appropriate pictorial representation.	Computer Graphic,Graphic, Computer,Graphics, Computer
D003553	Cystine	A covalently linked dimeric nonessential amino acid formed by the oxidation of CYSTEINE. Two molecules of cysteine are joined together by a disulfide bridge to form cystine.	Copper Cystinate,L-Cystine,L Cystine
D003594	Cytoplasmic Granules	Condensed areas of cellular material that may be bounded by a membrane.	Cytoplasmic Granule,Granule, Cytoplasmic,Granules, Cytoplasmic
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