| Proteocyte Diagnostics, Inc. | |
| ProteoGenex, Inc. | |
| Proteogenomics Research Institute for Systems Medicine | |
| ProteoNova, Inc. | California |
| Proteos, Inc. | |
| Proteovista, LLC | Wisconsin |
| Proteowise | Connecticut |
| Protequus, LLC | |
| Protera | Illinois |
| Proterra | California |
| Proteus B2B Marketing | Michigan |
| Proteus Genomics | Alabama |
| Proteus Technologies, LLC | |
| Proteus.co | Nebraska |
| ProTEXT | Utah |
| ProThera Biologics, Inc. | Rhode Island |
| Protide Pharmaceuticals, Inc. | |
| Protillion Biosciences | California |
| Proto-Tel, Inc. | Colorado |
| ProtoCAM | Pennsylvania |
| Protocase | New York |
| Protochips, Inc. | North Carolina |
| Protocol 80, Inc. | Pennsylvania |
| Protocol Communications, Inc. | Ohio |
| Protocol Driven Healthcare, Inc. | New Jersey |
| Protocol Infotech, Inc. | Florida |
| Protocol Labs | California |
| Protocol Three, LLC | |
| ProtoDev | |
| Protofire | |
| ProtoFuse | |
| ProtoKinetix, Inc. | Ohio |
| Protoline, Inc. | Texas |
| ProtoLink, Inc. | Texas |
| ProTom International | Massachusetts |
| Protomer Technologies, Inc. | California |
| Proton Technologies | North Carolina |
| Proton.ai | Massachusetts |
| Protonet, Inc. | California |
| ProtonSolutions | |
| Protopia AI | Texas |
| Protos Software, LLC | Arizona |
| Protosoft | Washington |
| Prototype:IT | Texas |
| Prototypical Design | |
| ProTrain, LLC | |
| ProTrials Research, Inc. | California |
| ProTronics Technologies, Inc. | Missouri |
| Protus3 | North Carolina |
| Proud Data Services | California |