MjK1, a K+ channel from M. jannaschii, mediates K+ uptake and K+ sensitivity in E. coli.

The methanogenic and hyperthermophilic deep-sea archaeon Methanococcus jannaschii has three putative K+ channels, MVP (Mj0139), MjK1 (Mj0138.1) and MjK2 (Mj1357). The physiological function of these K+ channels was examined in a viability assay, using the Escherichia coli mutant LB2003 (kup1, DeltakdpABC5, DeltatrkA).

Conserved arginine and aspartate residues are critical for function of MjNhaP1, a Na+/H+ antiporter of M. jannaschii.

Recently MjNhaP1 was identified as a pH-regulated Na(+)/H(+) antiporter of Methanococcus jannaschii [Hellmer, J. et al. (2002) FEBS Lett.

Identification of a pH regulated Na(+)/H(+) antiporter of Methanococcus jannaschii.

The genome of the hyperthermophilic archaeon Methanococcus jannaschii contains three Na(+)/H(+) antiporter related genes Mj0057, Mj1521 and Mj1275. Comparative sequence alignments revealed that Mj0057 and Mj1521 belong to the NhaP family whereas Mj1275 is a member of the NapA family. The genes were cloned and expressed in the double mutant Escherichia coli strain Frag144 (DeltanhaA, DeltanhaB) to analyze their capability of mediating DeltapH driven Na(+) flux in everted vesicles.

In situ lipolytic responses to isoproterenol and physiological stressors are similar in obese Pima Indians and Caucasians.

Evidence suggests that impaired lipolysis may contribute to fat accumulation. To test whether the lipolytic response to adrenergic stimulation is lower in Pima Indians, a population prone to obesity and type 2 diabetes mellitus, than in Caucasians, 48 healthy, non-diabetic subjects were studied: 27 Pima Indians (12 males and 15 females, 30 +/- 7 yr, 85 +/- 18 kg, 36 +/- 10% body fat; mean +/- SD) and 21 Caucasians (11 males and 10 females, 34 +/- 7 yr, 105 +/- 26 kg, 39 +/- 11% body fat). Lipolysis in the abdominal s.

Whole body fat oxidation is related to in situ adipose tissue lipolytic response to isoproterenol in males.

A high 24-h respiratory quotient (RQ), i.e., low fat oxidation, predicts weight gain.