The phrase "a functional portion" is correct and usable in written English.
It can be used to refer to a part of something that serves a specific purpose or function.
Example: "In the design of the software, we focused on creating a functional portion that would enhance user experience."
Alternatives: "a practical segment" or "a usable part".
Mr. Kapor said he planned to release a functional portion of the program by the end of the year, and hoped to have a finished product by the end of 2003.
Ebstein's anomaly is characterized by apical displacement of the tricuspid valve leaflets into the RV, which divides the RV into an "atrialized" portion and a "functional" portion with intrinsic musculature, both of which show varying degrees of dysplasia, fibrosis and thinning.
When you say "ad-supported," it conjures images of ugly banner ads surrounding the functional portion of the program or service.
After the federal e-commerce website spectacularly failed at its launch on October 1st, the only consistently functional portion of the website was the front page.
In addition, the functional portion of rAH was readily separated and recovered from the aggregates after extraction (Fig. 5B).
Science stuck to its maximalist guns, and its summary of 2012 repeated the claim that the "functional portion" of the human genome equals 80% (Anonymous 2012).
Multiple alignment showed higher identity and similarity between the C termini of paralogs, which contain the functional portion of the proteins.
The functional portion of the metabolic network includes glutamatergic neurotransmission, transmitter recycling and ionic movements, that together establish the coupling between activity and metabolism through the action of the Na/K-ATPase [ 33].
Non-synonymous changes in key functional portions of a major transcription factor are likely to be deleterious but if maintained in a dominant allele at low frequency, heterozygosity would reduce the associated genetic load.
Therefore, the data presented here suggest that structural modification of functional portions of an siRNA duplex by base substitution could greatly influence allele discrimination and gene silencing, thereby contributing to enhancement of ASP-RNAi.
Although this large evolutionary distance would imply that only a rather small fraction of the functional portions of their genomes are shared, comparative studies revealed that most human coding sequences (~91%) are homologous to genes in fish [ 5].
