Table II. Known β-actin-interacting proteins co-purified with ERα by IgG-Sepharose affinity chromatography and identified by nano-LC-MS/MS analysis.

The list of β-actin-interacting proteins from the UniHI database was crossed with the list of proteins co-purified with TAP-ERα, but not with the TAP tag alone, and identified by nano-LC-MS/MS analysis of purified samples. Proteins are listed with information relative to the MS data that led to their identification. Two identified proteins not listed as validated direct interactors of actin in the UniHI database and ERα itself are reported in bold. n/a, not applicable.

Protein ID (Swiss-Prot)	Protein name	Gene name	No. of peptides matched	Sequence coverage	Mowse score	Confirmed by WB
				%
P03372	Estrogen receptor	ESR1	2	6	97	n/a
P60709	Actin, cytoplasmic 1	ACTB	20	53	2509	+
P68032	Actin, α cardiac muscle 1	ACTC1	14	24	1901
P11142	Heat shock cognate 71-kDa protein	HSPA8	9	18	294
P06748	Nucleophosmin	NPM1	9	31	234	+
Q07020	60 S ribosomal protein L18	RPL18	5	24	206
P17844	Probable ATP-dependent RNA helicase DDX5	DDX5	14	22	182	+
P05388	60 S acidic ribosomal protein P0	RPLP0	9	39	180
P62424	60 S ribosomal protein L7a	RPL7A	7	19	113
P60660	Myosin light polypeptide 6	MYL6	4	30	104
P18124	60 S ribosomal protein L7	RPL7	6	25	88
P62701	40 S ribosomal protein S4, X isoform	RPS4X	8	26	79
P06396	Gelsolin	GSN	5	6	77	+
O00159	Myosin 1c	MYO1C	9	9	72	+
O00571	ATP-dependent RNA helicase DDX3X	DDX3X	4	5	71
P46781	40 S ribosomal protein S9	RPS9	7	29	62
P62241	40 S ribosomal protein S8	RPS8	4	21	61
P61158	Actin-related protein 3	ACTR3	2	7	58	+
P61160a	Actin-related protein 2	ACTR2	1	1	32	+

^a Raw MS/MS fragmentation data and Mascot search results included as supplemental data.