Figure 3. SDS–PAGE (left panel) and western-blot
analyses (right panel) of thylakoid membranes isolated from
Prochlorococcus MIT 9313 cells grown in the presence
(+Fe) and absence (-Fe) of iron. The expression of the pcbB
(PMT 0496) gene under -Fe conditions gives rise to an additional
band in the SDS–PAGE gel, where PcbA and PcbB proteins
are marked by black and white asterisks, respectively. The identity
of these proteins was confirmed by N-terminal sequencing giving
MQTYGNPN for PcbA and MQTYGKTD for PcbB. The antibodies for
detecting the level of PSII were raised against PsbA (D1 protein)
and for PSI raised against PsaC (FA/FB protein). The blotting
indicates that the PSI:PSII ratio remains about the same for
+Fe and -Fe cells.
