start-ver=1.4 cd-journal=joma no-vol=281 cd-vols= no-issue= article-no= start-page=111174 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2026 dt-pub=202601 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=N-terminal domains and site-specific glycosylation regulate the secretion of avian melanocortin inverse agonists, agouti signaling protein (ASIP) and agouti-related protein (AGRP) en-subtitle= kn-subtitle= en-abstract= kn-abstract=Agouti signaling protein (ASIP) and agouti-related protein (AGRP) are paralogous inverse agonists of melanocortin receptors with distinct physiological roles, but their structural and biochemical properties in birds remain poorly understood. Here, we characterized chicken ASIP and AGRP proteins. Analysis of available sequences revealed that a motif resembling the mammalian proprotein convertase 1/3 (PC1/3, also known as PCSK1) cleavage site is conserved across a broad range of avian orders, but Western blot analysis of transfected Chinese hamster ovary (CHO-K1) cells and chicken hypothalamus detected no cleavage, suggesting that avian AGRP may not be post-translationally processed at this site. Chicken ASIP mRNA contains an in-frame upstream ATG (uATG) and a putative N-linked glycosylation site at Asn-42, both conserved across multiple avian orders. Overexpression in CHO-K1 cells showed that ASIP translated from either ATG produces a mature protein of the same size that is N-glycosylated at Asn-42 and exhibits markedly lower secretion efficiency than AGRP. Domain-swapping experiments revealed that the N-terminal domain reduces secretion, whereas a naturally occurring ASIP-b variant with an additional N-glycan at Asn-47 shows enhanced secretion. Proteasome inhibition increased intracellular ASIP, and endoglycosidase H (Endo H) sensitivity indicated endoplasmic reticulum (ER) retention, suggesting that the N-terminal domain limits secretion via ER-associated proteasomal degradation. These findings reveal species-specific post-translational regulation of avian melanocortin inverse agonists, in which N-terminal features and site-specific N-glycosylation determine secretion efficiency, likely contributing to their distinct roles in pigmentation and hypothalamic energy balance. en-copyright= kn-copyright= en-aut-name=FukuchiHibiki en-aut-sei=Fukuchi en-aut-mei=Hibiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=WatanabeRyoya en-aut-sei=Watanabe en-aut-mei=Ryoya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=IidaYuna en-aut-sei=Iida en-aut-mei=Yuna kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NakanoSaya en-aut-sei=Nakano en-aut-mei=Saya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MizutaniAya en-aut-sei=Mizutani en-aut-mei=Aya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=AboTatsuhiko en-aut-sei=Abo en-aut-mei=Tatsuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=AizawaSayaka en-aut-sei=Aizawa en-aut-mei=Sayaka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=TakeuchiSakae en-aut-sei=Takeuchi en-aut-mei=Sakae kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=8 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=Agouti signaling protein kn-keyword=Agouti signaling protein en-keyword=Agouti-related protein kn-keyword=Agouti-related protein en-keyword=Avian melanocortin inverse agonists kn-keyword=Avian melanocortin inverse agonists en-keyword=Post-translational modification kn-keyword=Post-translational modification en-keyword=N-linked glycosylation kn-keyword=N-linked glycosylation en-keyword=Protein secretion kn-keyword=Protein secretion END start-ver=1.4 cd-journal=joma no-vol=95 cd-vols= no-issue=3 article-no= start-page=119 end-page=131 dt-received= dt-revised= dt-accepted= dt-pub-year=2020 dt-pub=20200601 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Ribosome rescue activity of an Arabidopsis thaliana ArfB homolog en-subtitle= kn-subtitle= en-abstract= kn-abstract=A homolog of the bacterial ribosome rescue factor ArfB was identified in Arabidopsis thaliana. The factor, named AtArfB for Arabidopsis thaliana ArfB, showed ribosome rescue activity in both in vivo and in vitro assays based on the bacterial translation system. As has been shown for ArfB, the ribosome rescue activity of AtArfB was dependent on the GGQ motif, the crucial motif for the function of class I release factors and ArfB. The C-terminal region of AtArfB was also important for its function. The N-terminal region of AtArfB, which is absent in bacterial ArfB, functioned as a transit peptide for chloroplast targeting in tobacco cells. These results strongly suggest that AtArfB is a ribosome rescue factor that functions in chloroplasts. en-copyright= kn-copyright= en-aut-name=NagaoMichiaki en-aut-sei=Nagao en-aut-mei=Michiaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TsuchiyaFumina en-aut-sei=Tsuchiya en-aut-mei=Fumina kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MotohashiReiko en-aut-sei=Motohashi en-aut-mei=Reiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=AboTatsuhiko en-aut-sei=Abo en-aut-mei=Tatsuhiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Integrated Science and Technology, Shizuoka University kn-affil= affil-num=3 en-affil=Graduate School of Integrated Science and Technology, Shizuoka University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Arabidopsis thaliana kn-keyword=Arabidopsis thaliana en-keyword=ArfB kn-keyword=ArfB en-keyword=chloroplast kn-keyword=chloroplast en-keyword=ribosome rescue kn-keyword=ribosome rescue en-keyword=translation kn-keyword=translation END