Characterization of a novel binding partner of the melanocortin-4 receptor: attractin-like protein.
The gene dosage effect of the MC4-R (melanocortin 4 receptor) on obesity suggests that regulation of MC4-R expression and function is critically important to the central control of energy homoeostasis. In order to identify putative MC4-R regulatory proteins, we performed a yeast two-hybrid screen of a mouse brain cDNA library using the mouse MC4-R intracellular tail (residues 303-332) as bait. We report here on one positive clone that shares 63% amino acid identity with the C-terminal part of the mouse attractin gene product, a single-transmembrane-domain protein characterized as being required for agouti signalling through the melanocortin 1 receptor. We confirmed a direct interaction between this ALP (attractin-like protein) and the C-terminus of the mouse MC4-R by glutathione S-transferase pulldown experiments, and mapped the regions involved in this interaction using N- and C-terminal truncation constructs; residues 303-313 in MC4-R and residues 1280-1317 in ALP are required for binding. ALP is highly expressed in brain, but also in heart, lung, kidney and liver. Furthermore, co-localization analyses in mice showed co-expression of ALP in cells expressing MC4-R in a number of regions known to be important in the regulation of energy homoeostasis by melanocortins, such as the paraventricular nucleus of hypothalamus and the dorsal motor nucleus of the vagus.
Haqq
Andrea M
AM
Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
René
Patricia
P
Kishi
Toshiro
T
Khong
Kathy
K
Lee
Charlotte E
CE
Liu
Hongyan
H
Friedman
Jeffrey M
JM
Elmquist
Joel K
JK
Cone
Roger D
RD
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D009474:Neurons / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D044105:Receptor, Melanocortin, Type 4 / Q000032:analysis / Q000378:metabolism*; D016415:Sequence Alignment; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; C480020:Atrnl1 protein, mouse; D002352:Carrier Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D044105:Receptor, Melanocortin, Type 4