The SLC6/NSS family members KAAT1 and CAATCH1 have weak chloride dependence.

KAAT1 and CAATCH1 are amino acid transporters cloned from the intestine of the lepidoptera Manduca sexta. They are members of the SLC6/NSS family, which groups membrane proteins that use Na(+), K(+), and Cl⁻ gradients for the coupled transport of amines and amino acids. The report of the atomic-resolution x-ray crystal structure of the eubacterium Aquifex aeolicus leucine transporter (AaLeuT) has contributed significantly to understanding of the structure-function relationship in NSS proteins.

Atomic force microscopy imaging of Xenopus laevis oocyte plasma membrane purified by ultracentrifugation.

Atomic force microscopy (AFM) was used to investigate the native plasma membrane of Xenopus laevis (X. laevis) oocyte purified by means of ultracentrifugation on sucrose gradient and subsequently adsorbed on mica leaves through a physisorption process. Reproducible AFM topography images were collected, analyzed, and compared.

Structural and functional basis of amino acid specificity in the invertebrate cotransporter KAAT1.

The substrate specificity of KAAT1, a Na+- and K+-dependent neutral amino acid cotransporter cloned from the larva of the invertebrate Manduca sexta and belonging to the SLC6A gene family has been investigated using electrophysiological and radiotracer methods. The specificity of KAAT1 was compared to that of CAATCH1, a strictly related transporter with different amino acid selectivity. Competition experiments between different substrates indicate that both transporters bind leucine more strongly than threonine and proline, the difference between KAAT1 and CAATCH1 residing in the incapacity of the latter to complete the transport cycle in presence of leucine.