Characterization of CBS-1 mutations and expression pattern. (A) Representative images of lysosomes in the hypodermis of WT and yq399 animals (2 days after L4) co-expressing YFP::2x FYVE and NUC-1::mCh. Bars, 5 μm. (B) Diagram of the cbs-1 gene (top) and comparison between C. elegans CBS-1 and human CBS (bottom). In the top diagram, solid boxes represent exons, and thin angled lines represent introns. The yq357 premature stop codon and yq399 substitution mutation are indicated. In C. elegans CBS-1 and human CBS, the pyridoxal-phosphate dependent (PLP) domains, CBS1/2 domains (CBS regulatory domains), and Heme-binding domain are indicated. The AA similarities (%) between the PLP domain in human CBS and the two PLP domains in C. elegans CBS-1 are indicated in blue and red. (C) Alignment of AA sequences of human CBS (H.s.) and C. elegans CBS-1 (C.e.). Identical AA residues are shaded in red. The PLP domains of both proteins are boxed. (D) Expression CBS-1::GFP(KI) in adult hypodermis and body wall muscles. Left and right panels are GFP and DIC images, respectively. Scale bars, 5 μm. DIC, differential interference contrast.