Convert the verb 'okumak' (to read) into a gerund using the nominalizing suffix '-ma' to create a noun phrase that can function as the subject of a sentence.

The verb 'okumak' means 'to read' in its infinitive form. To convert this verb into a gerund using the nominalizing suffix '-ma' so it can function as the subject of a sentence, we first need to identify the verb stem. The verb stem is the base part of the verb, derived by removing the infinitive suffix '-mak' or '-mek'. For 'okumak', the verb stem is 'oku'.

Next, we apply the nominalizing suffix '-ma' (or its vowel-harmonized counterpart '-me') to this verb stem. This suffix serves to transform a verb into a noun, typically denoting the action itself. The choice between '-ma' and '-me' is determined by the last vowel of the verb stem, adhering to two-way vowel harmony. If the last vowel of the stem is 'a', 'ı', 'o', or 'u', the suffix used is '-ma'. If the last vowel is 'e', 'i', 'ö', or 'ü', the suffix used is '-me'. In the verb stem 'oku', the last vowel is 'u', which dictates the use of the '-ma' suffix.

Attaching '-ma' to the verb stem 'oku' yields 'okuma'. This resulting word, 'okuma', is a gerund; it has transitioned from a verb form to function as a noun, meaning 'reading' or 'the act of reading'.

As a noun, 'okuma' can now readily serve as the subject of a sentence. The subject is the part of the sentence that performs or is the focus of the verb's action. For instance, in the sentence "Okuma önemlidir." (Reading is important.), 'okuma' is the subject. It is the entity being described as 'important', thereby forming a simple noun phrase that functions as the subject.