This family of proteins have been implicated in chlorophyll degradation [1,2]. Intriguingly members of this family are also found in non-photosynthetic bacteria.

1: Identification of a novel chloroplast protein AtNYE1 regulating chlorophyll degradation during leaf senescence in Arabidopsis. Ren G, An K, Liao Y, Zhou X, Cao Y, Zhao H, Ge X, Kuai B; Plant Physiol. 2007;144:1429-1441. PMID:17468209

2: The senescence-induced staygreen protein regulates chlorophyll degradation. Park SY, Yu JW, Park JS, Li J, Yoo SC, Lee NY, Lee SK, Jeong SW, Seo HS, Koh HJ, Jeon JS, Park YI, Paek NC; Plant Cell. 2007;19:1649-1664. PMID:17513504