TABLE 2.

Extracellular proteins of B. subtilis 168 without typical export signals^a

Protein	Function or similarity	% Cytoplasmic abundanceb	Mediumc
CitH	Malate dehydrogenase	1.20	LB
CwlCw ex	N-Acetylmuramoyl-l-alanine amidase	−	LB
Ef-G	Elongation factor G	1.91	LB
Eno	Enolase	1.23	LB, PS
FlgKex	Flagellar hook-associated protein 1	−	LB
FliDex	Flagellar hook-associated protein 2	−	LB
GapA	Glyceraldehyde-3-phosphate	1.20	MG,C,M,S
GroEL	Class I heat shock protein (chaperonin)	1.30	LB, PS
Hagdual	Flagellin protein	1.27	LB, PS, MG,C,M,S
KatAex	Vegetative catalase 1	−	LB, PS, MM
PdhA	Pyruvate dehydrogenase (E1 α subunit)	0.71	LB
PdhB	Pyruvate dehydrogenase (E1 β subunit)	0.57	LB
PdhD	Pyruvate dehydrogenase (E3 subunit)	0.76	LB, PS
RocA	Pyrroline-5 carboxylate dehydrogenase	−	LB
RocF	Arginase	−	LB
SodA	Superoxide dismutase	1.07	LB, PS, MG,M,S
XepAex	PBSX prophage lytic exoenzyme	−	LB
XkdGex	PBSX prophage gene	−	LB, MG
XkdKex	PBSX prophage gene	−	LB, PS
XkdMex	PBSX prophage gene	−	LB, PS
XlyAw ex	N-Acetylmuramoyl-l-alanine amidase	−	LB
YceD	Similar to tellurium resistance protein	−	LB
YvgNd	Similar to plant metabolite	−	LB
YwjH	Similar to transaldolase (pentose)	0.37	LB

^aAll listed proteins were identified by 2D PAGE and subsequent MALDI-TOF mass spectrometry and/or N-terminal amino acid sequencing as described by Hirose et al. (46), Antelmann et al. (5), and Vitikainen et al. (147). Proteins with a known dual localization (cellular and extracellular) are labeled^dual, proteins that lack a typical signal peptide but have a known extracytoplasmic localization are labeled^ex, and proteins containing cell wall-binding repeats are marked with^W.

^bRelative protein levels are expressed as the percentage of total protein content. Protein levels were determined by 2D PAGE of cytoplasmic protein extracts of B. subtilis cells grown in minimal medium with glucose (22). A minus (−) means that the cytoplasmic abundance is lower than 0.37%.

^cProteins found in the extracellular proteomes of cells grown in LB broth (rich medium) 5), phosphate-starvation medium (PS) (4), or minimal medium with glucose (M_G), cellobiose (M_C), maltose (M_M), or starch (M_S) (46).

^dThe YvgN protein was recently renamed FbaA (147).