The phrase "predominant portion" is correct and usable in written English.
You can use it to refer to a major part of something in comparison to the other parts. For example, "The predominant portion of office staff are working remotely due to the pandemic."
The predominant portion of gross violations of human rights was committed by the former state through its security and law-enforcement agencies.
The predominant portion of the endosperm is mucilage or gum (guar gum), which forms a viscous gel in cold water.
Animal diseases were for many years recognized as important constraints to livestock production and formed a predominant portion of donor funded programmes.
The Core set form a predominant portion of operons with 47% (2129 out of 4506 genes catalogued in RegulonDB version 5.7) of the operons consisting of Core genes, whereas 21% (948 out of 4506) of Non-core genes and 23% (1020 out of 4506) HGT genes, respectively, accounted for the remaining gene constituents of operons.
The Borana are predominant in the central portion of the study area, extending from Yabello in Ethiopia southward into Isiolo district of Kenya.
In this study, S. epidermidis is overall the predominant organism colonizing gastroesophageal portion of the GI tract throughout the first four weeks of life.
Chain-end control was predominant for producing the isotactic portion.
This results suggest a predominant contribution of the Costal portion of the diaphragm in order to generate the tidal volume during hypercapnic stimulation.
Such a pattern of changes might indicate predominant deterioration of the distal portion of the peripheral nerve or delay in chemical transmission between nerve terminals and muscle.
It was found that the trans-1,4 structure is predominant in the amorphous polymer and the portion of 1,2-structure is relatively fixed.
In larger lesions, the peripheral aspect of the tumour receives a better blood supply than the more hypovascular central portion, which results in a predominant ring enhancement pattern on early postcontrast images.
