calcium pump. the mechanism of active transport of calcium (Ca 2+) across a membrane, as of the sarcoplasmic reticulum of muscle cells, against a concentration gradient; the mechanism is driven by hydrolysis of ATP.
A rental agreement differs from a lease agreement in that it is not a long-term contract and usually occurs on a month-to-month basis. This month-to-month lease agreement expires and then renews each month upon agreement of the parties involved.
With a lease option, there are only a couple of required elements, and everything else is negotiable between the individual tenant/buyer and landlord/seller. The way it works is that the tenant leases the home from the landlord. The lease agreement sets up a certain rental rate, and a certain lease term. The agreement also expressly gives the tenant the right, or option, to purchase the property on or after a certain date, at a certain price.