Unit Conversion Table: Protein Reference Standards
A unit is defined according to the standard by which it is compared. For instance, the World Health Organization (WHO) offers protein reference standards that are accessible to everyone and allow for the normalization of activity definitions across proteins from different sources. These are available from NIBSC.
The activity of the protein reference standard is indicated by the number of units contained in a given mass of material. Typically, units are referred to as reference units (RU). When the reference material has been tested successfully in international, multi-center, collaborative studies it will be designated a WHO international standard, the units will then be International units (IU).
If there is a protein reference standard available, R&D Systems compares the activity of the reference standard with our protein, allowing for the conversion of mass into units (see table below).
Are all units the same?
No. One must be careful when comparing units of activity between sources. Different suppliers may have their own method for defining a unit. The method used, such as comparison with a WHO standard, must be the same between sources for a unit comparison to be valid. For this reason R&D Systems typically refers to proteins by their mass and activity by ED50.
Sample Conversion R&D Systems Recombinant Human BMP-2 to Equivalent Units
To calculate the approximate mass/concentration of an R&D Systems cytokine in units, multiply the mass/concentration (in µg) by the ‘R&D Systems Cytokine 1 µg = units’ column in the chart, the second column from the right. For instance, a 10 µg vial of rhBMP-2, catalog #355-BM, would contain 7,810 units (10 times 781).
| R&D Systems Cytokine | R&D Systems Catalog Number | Reference Cytokine | NIBSC Product Number | Reference Standard Units/µg | Cell Line used for Bioassay | R&D Systems Cytokine 1 µg = units |
| rhActivin A | 338-AC | rhActivin A | 91/626 | 1 | K562 | 2.5 |
| rhBDNF | 248-BD | rhBDNF | 96/534 | 800 | BaF/3 hTrkB | 1.3 x 103 |
| rhBDNF New! | 11166-BD | rhBDNF | 96/534 | 800 | BaF/3 hTrkB | 1.4 x 103 |
| rhBMP-2 | 355-BM | rhBMP-2 | 93/574 | 500 | ATDC-5 | 781 |
| rhEGF | 236-EG | rhEGF | 91/530 | 1.0 x 103 | Balb-3T3 | 1.4 x 103 |
| rhFactor II | 1473-SE | hThrombin | 01/580 | 2.5 | Boc-VPR-AMC Fluor Pep Sub | 2.6 |
| rhFGF-7 | 251-KG | rhFGF-7 | 03/148 | 900 | 4MBr-5 | 520 |
| rhFGF basic | 233-FB | rhFGF basic | 90/712 | 800 | NR6R-3T3 | 2.6 x 103 |
| rhFGF basic | 3718-FB | rhFGF basic | 90/712 | 800 | NR6R-3T3 | 3.1 x 103 |
| rhFSH | 5925-FS | rhFSH | 92/642 | 13.8 | HEK293/h FSH R | 17.5 |
| rhFlt-3 Ligand | 308-FK | rhFlt-3 Ligand | 96/532 | 1.0 x 103 | Baflt | 1.2 x 103 |
| rhG-CSF | 214-CS | rhG-CSF | 88/502 | 1.0 x 105 | NFS-60 | 2.6 x 105 |
| rhGDNF | 212-GD | rhGDNF | 09/266 | 500 | SH-SY5Y | 3.1 x 103 |
| rhGH | 1067-GH | hGH | 80/505 | 2.6 x 10-3 | Nb2-11 | 5.4 x 10-3 |
| rhGM-CSF | 215-GM | rhGM-CSF | 88/646 | 1.0 x 104 | TF-1 | 1.5 x 104 |
| rmGM-CSF | 415-ML | rmGM-CSF | 91/658 | 1.0 x 105 | DA3 | 3.5 x 105 |
| rhGRO alpha | 275-GR | rhGRO alpha | 92/722 | 1.0 x 105 | PMN | 2.11 x 105 |
| rhHGF | 294-HG | rhHGF | 96/564 | 1.0 x 103 | Saos-2 | 1.5 x 103 |
| rhIFN-beta | 8499-IF | rhIFN-beta | 00/572 | 2.0 x 105 | HeLa | 2.8 x 105 |
| rhIFN-gamma | 285-IF | rhIFN-gamma | 87/586 | 2.0 x 104 | HeLa | 2.0 x 104 |
| rmIFN-beta | 8234-MB | mIFN-beta | NR-3079** | NA | L929 | 1.2 x 106 |
| rmIFN-gamma | 485-MI | rmIFN-gamma | NIHGg02-901-533 | 1.0 x 103 | L929 | 8.43 x 103 |
| rhIGF-I | 291-G1 | rhIGF-I | 91/554 | 1 | MCF-7 | 1.9 |
| rhIGF-II | 292-G2 | rhIGF-II | 96/538 | 1000 | MCF-7 | 850 |
| rhIL-1 alpha | 200-LA | rhIL-1 alpha | 86/632 | 1.0 x 105 | D10.G4.1 | 1.6 x 105 |
| rmIL-1 alpha | 400-ML | rmIL-1 alpha | 93/672 | 1.0 x 106 | D10.G4.1 | 7.1 x 105 |
| rhIL-1 beta | 201-LB | rhIL-1 beta | 86/680 | 1.0 x 105 | D10.G4.1 | 1.4 x 105 |
| rmIL-1 beta | 401-ML | rmIL-1 beta | 93/668 | 1.0 x 106 | D10.G4.1 | 1.1 x 106 |
| rhIL-1ra | 280-RA | rhIL-1ra | 92/644 | 1.0 x 10-3 | D10.G4.1 | 1.0 x 10-3 |
| rhIL-2 | 202-IL | rhIL-2 | 86/500 | 1.4 x 104 | CTLL-2 | 9.1 x 103 |
| rhIL-2 New! | BT-002 | rhIL-2 | 86/500 | 1.4 x 104 | CTLL-2 | 14.4 x 103 |
| rmIL-2 | 402-ML | rmIL-2 | 93/566 | 1.0 x 105 | CTLL-2 | 2.5 x 105 |
| rhIL-3 | 203-IL | rhIL-3 | 91/510 | 1.7 x 103 | TF-1 | 1.8 x 103 |
| rmIL-3 | 403-ML | rmIL-3 | 91/662 | 1.0 x 105 | NFS-6 | 1.7 x 105 |
| rhIL-4 | 204-IL | rhIL-4 | 88/656 | 1.0 x 104 | TF-1 | 1.7 x 104 |
| rhIL-4 New! | BT-004 | rhIL-4 | 88/656 | 1.0 x 104 | TF-1 | 2.0 x 104 |
| rmIL-4 | 404-ML | rmIL-4 | 91/656 | 1.0 x 104 | HT-2 | 1.8 x 105 |
| rhIL-5 | 205-IL | rhIL-5 | 90/586 | 1.0 x 104 | TF-1 | 4.4 x 104 |
| rhIL-6 | 206-IL | rhIL-6 | 89/548 | 1.0 x 105 | T1165.85.2.1 | 1.1 x 105 |
| rmIL-6 | 406-ML | rmIL-6 | 93/730 | 1.0 x 105 | T1165.85.2.1 | 9.0 x 105 |
| rhIL-7 | 207-IL | rhIL-7 | 90/530 | 1.0 x 105 | activated PBL | 1.6 x 105 |
| rhIL-7 New! | BT-007 | rhIL-7 | 90/530 | 1.0 x 105 | activated PBL | 2.0 x 105 |
| rmIL-7 | 407-ML | rmIL-7 | 93/740 | 5.0 x 104 | activated PBL | 1.5 x 105 |
| rhIL-8 | 208-IL | rhIL-8 | 89/520 | 1.0 x 103 | PMN | see below* |
| rhIL-9 | 209-IL | rhIL-9 | 91/678 | 1.0 x 104 | MO7e | 8.4 x 103 |
| rmIL-9 | 409-ML | rmIL-9 | 93/504 | NA | TS1 | 0.9 µg |
| rhIL-10 | 217-IL | rhIL-10 | 93/722 | 5.0 x 103 | MC/9 | 1.45 x 104 |
| rhIL-11 | 218-IL | rhIL-11 | 92/788 | 1.0 x 104 | T11 | 1.05 x 104 |
| rhIL-11 New! | 10836-IL | rhIL-11 | 92/788 | 1.0 x 104 | T11 | 1.02 x 104 |
| rhIL-12 | 219-IL | rhIL-12 | 95/544 | 1.0 x 104 | PBL | 1.1x 104 |
| rhIL-12 New! | 10018-IL | rhIL-12 | 95/544 | 1.0 x 104 | PBL | 1.54 x 104 |
| rhIL-13 | 213-ILB | rhIL-13 | 94/622 | 1.0 x 103 | TF-1 | 780 |
| rhIL-15 | 247-IL | rhIL-15 | 95/554 | 1.0 x 104 | MO7e | 4.5 x 105 |
| rhIL-15 New! | BT-015 | rhIL-15 | 95/554 | 1.0 x 104 | MO7e | 7.5 x 105 |
| rhLeptin | 398-LP | rhLeptin | 97/594 | 800 | BaF3/h OB R | 1.2 x 103 |
| rmLeptin | 498-OB | rmLeptin | 97/626 | 1.0 x 103 | BaF3/h OB R | 1.7 x 103 |
| rhLIF | 7734-LF | rhLIF | 93/562 | 1 x 104 | TF-1 | 1.27 x 104 |
| rhM-CSF | 216-MC | rhM-CSF | 89/512 | 6.0 x 104 | M-NFS-60 | 1.68 x 105 |
| rhMCP-1 | 279-MC | rhMCP-1 | 92/794 | 1.0 x 103 | MNC | 1.36 x 103 |
| rhMCP-2 | 281-CP | rhMCP-2 | 96/594 | 2.5 x 103 | MNC | see below* |
| rhMIP-1 alpha | 270-LD | rhMIP-1 alpha | 92/518 | 100 | MNC | 200 |
| rhMIP-1 beta | 271-BME | rhMIP-1 beta | 96/588 | 1.0 x 103 | MNC | 1.6 x 103 |
| rhbeta-NGF | 256-GF | rhbeta-NGF | 93/556 | 1.0 x 103 | TF-1 | 1.0 x 103 |
| rhNT-3 | 267-N3 | rhNT-3 | 98/718 | 1.0 x 103 | BaF/3 hTrkB | 2.1 x 103 |
| rhOSM | 295-OM | rhOSM | 93/564 | 5.0 x 104 | TF-1 | 6.2 x 104 |
| rhPDGF-BB | 220-BB | rhPDGF-BB | 94/728 | 750 | NR6R-3T3 | 1.9 x 103 |
| rhProlactin | 682-PL | rhProlactin | 84/500 | 0.0212 | Nb2-11 | 0.054 |
| rhRANTES | 278-RN | rhRANTES | 92/520 | 1.0 x 104 | MNC | 2.5 x 104 |
| rhSCF | 255-SC | rhSCF | 91/682 | 1.0 x 103 | TF-1 | 1.3 x 103 |
| rhSCF New! | BT-SCF | rhSCF | 91/682 | 1.0 x 103 | TF-1 | 1.8 x 103 |
| porcine TGF-beta 1 | 101-B1 | bTGF-beta 1 | 89/516 | 18750 | HT-2 | 2.1 x 104 |
| porcine TGF-beta 2 | 102-B2 | hTGF-beta 2 | 90/696 | 2.0 x 104 | HT-2 | 5.6 x 104 |
| rhTGF-beta | 240-B | rhTGF-beta 1 | 89/514 | 1.9 x 104 | HT-2 | 2.2 x 104 |
| rhTGF-beta New! | 7754-BH | rhTGF-beta 1 | 89/514 | 1.9 x 104 | HT-2 | 2.4 x 104 |
| rhTGF-beta 2 | 302-B2 | rhTGF-beta 2 | 90/696 | 2 x 104 | HT-2 | 2.2 x 104 |
| rhTGF-beta 3 | 243-B3 | rhTGF-beta 3 | 09/234 | 1.9 x 104 | HT-2 | 2.2 x 104 |
| rhTGF-beta 3 New! | 8420-B3 | rhTGF-beta 3 | 09/234 | 1.9 x 104 | HT-2 | 2.8 x 104 |
| rhTNF-alpha | 210-TA | rhTNF-alpha | 88/786 | 4.65 x 104 | L-929 | 7.6 x 104 |
| rmTNF-alpha | 410-MT | rmTNF-alpha | 88/532 | 2.0 x 105 | L-929 | 2.7 x 105 |
| rhTNF-beta | 211-TB | rhTNF-beta | 87/640 | 1.5 x 105 | L-929 | 4.6 x 104 |
| rhTRAIL | 375-TEC(E. coli) | rhTRAIL | 04/166 | 1.0 x 104 | L-929 | 5.6 x 103 |
| rhTRAIL | 375-TL(NS0) | rhTRAIL | 04/166 | 1.0 x 104 | L-929 | 3.2 x 103 |
| rhTSH | 4610-TH | rhTSH | 94/674 | 6.7 x 10-3 | HEK293/h TSH R | 7.9 x 10-3 |
| rhVEGF165 | 293-VE | rhVEGF165 | 02/286 | 1.0 x 103 | HUVEC | 1.1 x 103 |
| rhVEGF165 New! | BT-VEGF | rhVEGF165 | 02/286 | 1.0 x 103 | HUVEC | 0.9 x 103 |
* In side by side evaluation of this standard with R&D Systems product, the standard demonstrated much lower maximal signal and thus cannot be compared using ED50
**The reference material was obtained through the NIH Biodefense and Emerging Infections Research Resources Repository, NIAID, NIH.