biostudies-literatureUnknown17(15-16)Semba RDNational Institutes of HealthIntramural Research Program of the National Institute on AgingCirculating polypeptides and proteins have been implicated in reversing or accelerating aging phenotypes, including growth/differentiation factor 8 (GDF8), GDF11, eotaxin, and oxytocin. These proteoforms, which are defined as the protein products arising from a single gene due to alternative splicing and PTMs, have been challenging to study. Both GDF8 and GDF11 have known antagonists such as follistatin (FST), and WAP, Kazal, immunoglobulin, Kunitz, and NTR domain-containing proteins 1 and 2 (WFIKKN1, WFIKKN2). We developed a novel multiplexed SRM assay using LC-MS/MS to measure five proteins related to GDF8 and GDF11 signaling, and in addition, eotaxin, and oxytocin. Eighteen peptides consisting of 54 transitions were monitored and validated in pooled human plasma. In 24 adults, the mean Proteomicshttps://www.ebi.ac.uk/biostudies/studies/S-EPMC5863538biostudies-literatureA targeted proteomic assay for the measurement of plasma proteoforms related to human aging phenotypes.PMC5863538R01 AG027012R01 EY024596R56 AG052973Semba RDZhu MMoaddel RFabbri EGonzalez-Freire MGeng-Spyropoulos MFerrucci LZhang PfalseA targeted proteomic assay for the measurement of plasma proteoforms related to human aging phenotypes.Circulating polypeptides and proteins have been implicated in reversing or accelerating aging phenotypes, including growth/differentiation factor 8 (GDF8), GDF11, eotaxin, and oxytocin. These proteoforms, which are defined as the protein products arising from a single gene due to alternative splicing and PTMs, have been challenging to study. Both GDF8 and GDF11 have known antagonists such as follistatin (FST), and WAP, Kazal, immunoglobulin, Kunitz, and NTR domain-containing proteins 1 and 2 (WFIKKN1, WFIKKN2). We developed a novel multiplexed SRM assay using LC-MS/MS to measure five proteins related to GDF8 and GDF11 signaling, and in addition, eotaxin, and oxytocin. Eighteen peptides consisting of 54 transitions were monitored and validated in pooled human plasma. In 24 adults, the mean 2017-01-01T00:00:00Z2017 Aug2025-04-19T02:29:17.234Z2019-03-26T23:48:52ZS-EPMC58635382850855310.1002/pmic.201600232