The genes that underlie amino acid transport systems like the well-described mammalian systems have been cloned and characterized in a wide range of organisms (e.g., Malandro and Kilberg, 1996; Nelissen et al., 1997; Jack et al., 2000).
In contrast to the more detailed understanding of genes that regulate amino acid transport systems in model systems, far less is known about the corresponding genes involved in amino acid transport by marine invertebrates.
purpuratus, high-affinity amino acid transport systems are active throughout embryogenesis and larval development (Epel, 1972; Manahan et al., 1989).
The substrate specificity of neutral amino acid transport systems in sea urchin larvae was investigated by measuring the inhibition of alanine transport in the presence of other neutral amino acids present in molar excess.
The sodium dependency of these sea urchin genes is consistent with the extensive literature showing that integumental amino acid transport systems in echinoids and marine invertebrates, in general, are sodium-dependent (Epel.