Extended Data Fig. 4: Overall structure of the PBS from P. purpureum and comparison with that from G. pacifica.

a, Schematic diagram showing the organization of the rods and the core from two perpendicular views. The colouring scheme is the same as in Fig. 1e. b, Structure of the core from two perpendicular views shows the assembly and arrangement of the core layers. c, Overall structure of the PBS overlapped with the G. pacifica PBS displayed in surface representation from three perpendicular views. The additional hexamers in the G. pacifica PBS are coloured white and labelled. d, Schematic model of the PBS architecture. The connections between PBS components are shown. Dark and light colours show C2 symmetric parts of rods. Dark and light salmon, phycoerythrin hexamers in rod; dark and light brown, extra phycoerythrin hexamers; dark and light forest green, phycocyanin hexamers; blue, allophycocyanin trimer; large rectangular box, Pfam00427 domains; small rectangular box, Pfam01383 domains; square box, CBDγ. e, Comparison of linker proteins from P. purpureum with those from G. pacifica. Structures of the 19 well-resolved linker proteins (magenta) are superimposed with those from the G. pacifica PBS (cyan). The linker proteins share very high structural conservation—such as the Pfam00427 domain in the rod–core linker (L_RC)1–3/L_RC1′–3′, the rod linker (L_R)1–3/L_R1′–3′ and L_CM/L_CM′, the Pfam01383 domain in the core linker (L_C)/L_C′ and L_R1/ L_R1′, the FAS1 domain in L_RC6/L_RC6′ and L_R9/L_R9′, the CBDγ domain in L_Rγ4–5/L_Rγ4′–5′ and L_Rγ7–8/ L_Rγ7′–8′, the coiled-coil motif at the C termini of L_RC2–3/L_RC2′–3′, and the long α-helix in the middle of the L_RC4–5/L_RC4′–5′. Note that L_R6 from the P. purpureum PBS is different from L_Rγ6 from the G. pacifica PBS, therefore they are not aligned. Domains of \({{\rm{\alpha }}}^{{{\rm{L}}}_{{\rm{CM}}}}\), Pfam00427 (00427), Pfam01383 (01383), CBDγ, and FAS1 are labelled.