The phrase "are postulated to function" is correct and usable in written English.
It can be used in contexts where you are discussing theories or hypotheses about how something is believed to operate or behave.
Example: "In this study, certain mechanisms are postulated to function in the regulation of gene expression."
Alternatives: "are theorized to operate" or "are assumed to work".
Since Chi25 and Chi35 are produced in very low levels, they are postulated to function as antifungal agents rather than as major enzymes to digest chitin (Tsujibo et al. 2000a).
Members of the T2S D protein family, to which XpsD belongs, are postulated to function as gatekeepers for type II secretion, demonstrating species-specific function for different type II secretion substrates [105], [106].
Also of significance is the observation that the FAM19A5 protein encoded by the FAM19A5 gene (22q13.32) belongs to the TAFA protein family which are predominantly expressed in the brain, and are postulated to function as brain-specific chemokines or neurokines, that act as regulators of immune and nervous cells [32].
These proteins are postulated to function as important modulators of female post-mating responses.
The Ras association domain family 1 (RASSF1) proteins are postulated to function as Ras effectors and to affect cell growth.
The TAFA proteins are predominantly expressed in specific regions of the brain, and are postulated to function as brain-specific chemokines or neurokines, that act as a regulator of immune and nervous cells [ 72].
Unlike vacuolar-localized class I transporters, AtNHX5 and 6 class II transporters were postulated to function in endosomal vesicles (Pardo et al. [2006]).
These results are surprising because the ARFGAP1 has never been postulated to function in the cell periphery involving in actin regulation.
WhiB protein family members were postulated to function in cell division and septation of mycobacteria [31] and in differentiation of streptomycetes [32].
Reductions in inflammatory cell invasion and plaque growth followed M-T7 treatment in both rat and rabbit iliofemoral angioplasty balloon injury models, indicating that M-T7 anti-inflammatory activity is not IFNγ dependent but instead is postulated to function through chemokine modulation, in a species independent fashion [41].
BRCA1 protein is postulated to function as a tumour suppressor.
