TABLE 1.

NFX1-123 and copurified proteins identified by MS in tandem-affinity purification of 293T cells^a

Name	Accession no.	No. of peptides	No. unique
NFX1	U15306, NM_002504	33	18
Calmodulin		15	5
USP/FAFX	X98296	10	10
Inducible PABP, PABP4	NM_002568	9	8
Trypsin		8	4
Keratin		7	6
Elongation factor 1-α2	NM_001958	6	5
Matrin 3	NM_018834	6	6
Calmodulin 2		5	2
PABP3	NM_030979	5	5
Heat shock protein 70 protein 1	M59828	4	4
Heterogeneous nuclear ribonucleoprotein m	L03532	4	4
Heterogeneous nuclear ribonucleoprotein u	NM_031844	4	4
60S ribosomal protein L13a	X64707	3	2
Splicing factor, arginine/serine-rich 4	L14076	3	2
PABP1	NM_002568	3	3
Histone H2A type 1	M60752	3	3
Keratin		3	3
60S ribosomal protein 17a	X06705	3	3
40S ribosomal protein S2	BC001759	3	3
KIAA0731	NM_015315	3	3
Dead box protein p68; dead box protein 5	NM_004396	2	2
Dystrophin	M18533	2	2
Keratin		2	2
Keratin		2	2
IgG		2	2
Nucleolin	NM_005381	2	2
60S ribosomal protein L13a	X56932	2	2
60S ribosomal protein L17	X53777	2	2
60S ribosomal protein L22	X59357	2	2
60S ribosomal protein L3	X73460	2	2
60S ribosomal protein L6	X69391	2	2
Heterogeneous nuclear ribonucleoproteins A2/B1	NM_031243	2	2
Heterogeneous nuclear ribonucleoprotein H	L22009	2	2
40S ribosomal protein S19	M81757	2	2
40S ribosomal protein S3A	M77234	2	2
Splicing factor, arginine/serine-rich 3	NM_003017	2	2
APCL protein	NM_005883	2	2
Nuclease-sensitive element binding protein 1	BC002411	2	2
His1h4f protein	CR542189	2	2

^aNFX1 was the most abundant protein identified by MS. Two poly(A) binding proteins were identified in two independent purification studies (boldface). Other RNA-processing proteins and deubiquitinating protein were also identified. Accession numbers for proteins copurified with NFX1-123 are listed.