The present invention discloses Mnk homologous proteins regulating the energy homeostasis, the metabolism of triglycerides, and/or is contributing to membrane stability and/or function of organelles, and polynucleotides, which identify and encode the proteins disclosed in this invention. The invention also relates to the use of these sequences in the diagnosis, study, prevention, and treatment of diseases and disorders related to body-weight regulation and thermogenesis, for example, but not limited to, metabolic diseases such as obesity, as well as related disorders such as eating disorder, cachexia, diabetes mellitus, hypertension, coronary heart disease, hypercholesterolemia, dyslipidemia, osteoarthritis, gallstones, and sleep apnea, and disorders related to ROS defence, such as diabetes mellitus, neurodegenerative disorders, and cancer, e.g. cancers of the reproductive organs, and others.